Previous research has demonstrated that ingesting fluid of different temperatures results in different whole-body sweat losses (WBSL) and transient changes in local sweat rate (LSR) without any parallel differences in core or skin temperatures. The purpose of this thesis was to determine the potential location and relative contribution of gastrointestinal thermoreceptors that modify sudomotor activity. Eight participants cycled for 75 min while cold (1.5°C) and warm (50°C) water was either swilled in the mouth, or delivered directly to the stomach bypassing the mouth using a nasogastric tube, after 15, 30 and 45-min of exercise. Mouth-swilling warm or cold water did not alter sudomotor output, however delivering warm or cold water directly into the stomach led to a temperature-dependent change in sudomotor output, despite similar core and skin temperatures. These data indicate that thermoreceptors independently modulating sudomotor output probably reside within the abdominal area, but not the mouth.

Current knowledge indicates that nonthermal muscle metaboreflex activity plays a critical role in the modulation of skin vasodilation and sweating. However, the mechanisms of control have primarily been studied during isometric handgrip exercise in which muscle metaboreceptor activation is induced by a brief post-exercise ischemia of the upper limb. While the reflex increase in mean arterial pressure associated with this period of ischemia is consistent with the activation of muscle metaboreceptors, the change in baroreflex activity may in itself modulate the response. Thus, we sought to understand how these nonthermal stimuli interact in modulating the control of skin perfusion and sweating under conditions of elevated hyperthermia. Furthermore, we examined the mechanisms responsible for the maintenance of arterial blood pressure under varying levels of heat stress during isometric handgrip exercise. Our study findings indicate that the parallel activation of muscle metaboreceptors and baroreceptors during post-exercise ischemia causes divergent influences on the control of skin blood flow and sweating; and these nonthermal stimuli are dependent on the level of hyperthermia. Moreover, we report that heat stress reduces the increase in arterial blood pressure during isometric handgrip exercise and this attenuation is attributed to a blunted increase in peripheral resistance, since cardiac output increased to similar levels for all heat stress conditions. These results provide important insight and understanding into the role of muscle metabo- and baroreflex activity on the control of skin blood flow and sweating; along with further knowledge into the cardiovascular mechanisms responsible for the regulation of arterial blood pressure during hyperthermia.

Diss. (sammanfattning) Alnarp : Sveriges lantbruksuniversitet, 2004. / Härtill 4 uppsatser.

INTRODUÇÃO: O excesso de adiposidade é considerado um fator que prejudica a termorregulação durante exercício no calor; entretanto, isso não tem sido observado em alguns estudos que compararam adolescentes obesos e magros. Tal diferença entre estudos pode ser devida à falta de controle de fatores tanto individuais, como nível de condicionamento aeróbico, quanto metodológicos, como nível de hidratação e produção de calor metabólico. OBJETIVO: Testar a hipótese de que meninos obesos com condicionamento aeróbico e grau de hidratação similares aos de magros, apresentam prejuízos nas respostas termorregulatórias ou perceptivas ao se exercitarem num mesmo %VO2pico ou com mesma produção de calor metabólico. MÉTODOS: Foram recrutados para este estudo 50 meninos púberes, sendo quatro desses excluídos por critérios de sobrepeso. No total, 46 (23 obesos e 23 magros), aclimatizados ao calor e com similar VO2pico por massa muscular, participaram do protocolo experimental. Entre esses, 41 meninos foram categorizados de acordo com seu condicionamento aeróbico: 20 (10 obesos e 10 magros) apresentavam alto condicionamento – “highfit” (HIfit); e 21 (10 obesos e 11 magros), baixo condicionamento – “lowfit” (LOfit). Todos pedalaram por dois períodos de 25 min, separados por 10 min de intervalo, dentro de uma câmara ambiental (35°C, 40-45% de umidade relativa), em duas sessões diferentes apenas quanto ao alvo de intensidade do exercício: 1) intensidade relativa (IR) a 40-45% do VO2pico; e 2) produção de calor metabólico fixada (PCMF) em 5,5 W.kg-1. A temperatura retal (Tretal), a temperatura da pele (Tpele) e a frequência cardíaca (FC) foram avaliadas continuamente, e variáveis perceptivas (de esforço, sensação térmica e conforto térmico) foram registradas a cada 5 min. A massa corporal foi medida antes e após cada 25 min de exercício para calcular o balanço hídrico e o volume de suor. Os meninos mantiveram-se hidratados, ingerindo, no intervalo de 10 min, um volume de água semelhante às perdas de suor decorrentes dos primeiros 25 min de exercício. RESULTADOS: O aumento na Tretal até o final do exercício foi discreto e similar entre obesos e magros, mesmo quando os grupos foram categorizados em HIfit e LOfit. Tal similaridade foi observada também no aumento da Tpele entre os grupos. No geral, a FC foi maior nos obesos em alguns momentos da sessão IR e ao longo de quase todo o exercício da sessão PCMF. Mas, quando categorizados pelo condicionamento aeróbico, foi maior em OB-LOfit vs. magros (HIfit e LOfit) no minuto 40 da sessão IR, e maior em OB-LOfit vs. MA-HIfit no minuto 50 da sessão PCMF. Entretanto, isso não foi acompanhado pela percepção de esforço nas duas sessões de exercício, nem mesmo pela sensação de calor ou desconforto térmico. CONCLUSÃO: Quando o alvo de intensidade para o exercício foi fixado pela PCM ou relativo ao VO2pico, e a hidratação foi controlada, nenhuma desvantagem termorregulatória ou de percepção ao calor foi observada por parte dos obesos, independentemente do seu condicionamento aeróbico. / INTRODUCTION: Excess adiposity is considered a factor which impairs thermoregulation during exercise in the heat. However, in adolescents, previous studies showed either similar or greater increase in rectal temperature (Tre) in obese compared to lean while exercising in the heat. The differences amongst studies may be due to lack of controlling factors such as metabolic heat production (Hprod), aerobic fitness and hydration levels. PURPOSE: To test the hypothesis that obese compared to lean adolescent boys with similar aerobic fitness and hydration levels will have greater Tre increase when exercising in the heat in a given Hprod. METHODS: Fifty pubertal boys were recruited for this study; four of these were excluded because overweight criteria; and a total of 46 (23 obese e 23 lean pubertal), heat-acclimatized, and with similar VO2peak by total muscle mass, participated in the experimental protocol. Among these, 41 boys were categorized according to their aerobic fitness: 20 (10 obese e 10 lean) were high fit (HIfit), and 21 (10 obese e 11 lean) were low fit (LOfit). All performed two 25-min exercise bouts, separated by 10-min rest in a controlled hot environment (35°C, 40-45% RH), in two sessions which only differed as the exercise intensity target: 1) relative intensity (RI) 40-45%VO2peak; and 2) metabolic heat production fixed (HProd) of 5.5 W.kg-1. Tre, skin temperature (Tskin) and heart rate (HR) were evaluated continuously, and perceptual variables (thermal sensation and thermal comfort) were recorded every 5 min. Body mass was measured before and after each exercise bout to calculate water balance and sweat volume. Boys kept hydrated as water volume intake at rest (between bouts) was similar to sweat losses from the 1st bout. RESULTS: The increase in Tre was discreet and similar between obese and lean boys at the end of exercise, even when the groups were categorized as HIfit and LOfit. It was also observed to Tskin increase. Overall, HR was higher in obese at times of the RI session, and for almost the entire Hprod session. But, when categorized by VO2peak, HR was higher in obese LOfit vs. lean (HIfit and LOfit) in the RI session (in 40th min) and higher in obese LOfit vs. lean HIfit in the Hprod session (in 50th min). However, this was not accompanied by the perception of effort in two exercise sessions, not even by the heat sensation or thermal discomfort. CONCLUSION: When the intensity target of exercising was fixed to Hprod or relative to VO2peak and hydration was controlled, as well as fitness level, no difference was found in the increase in Tre or sweat volume between groups. Therefore, our hypothesis was not verified, because no disadvantage in thermoregulatory or heat perception was observed in the obese group, regardless of aerobic fitness.

Life underground is one of the most challenging tasks for animals. The subterranean environment is seasonally and diurnally stable and provides shelter from predators. On the other hand food is scarce, the cost of digging is very high and closed burrows create hypoxic and hypercapnic conditions. Thus the physiological and behavioral adaptations to save energy are very important for underground dwellers. Social thermoregulation is such behavioral adaptation. Additionally, it has been suggested that social animals suffer from ?isolation stress? and that they decrease their metabolic rates when other family members are present = socio-physiological effect. In this study I measured the resting metabolic rates (RMR) of social Mashona mole-rats (Fukomys darlingi) in isolated individuals, pairs and groups of three to eight individuals. Measurements were carried out at two ambient temperatures, in the thermoneutral zone (TNZ; 30°C) to test the presence of a socio-physiological effect and below their TNZ (20°C) to test the effect of social thermoregulation. A socio-physiological effect was distinctive neither in pairs nor in larger groups. At temperature below the TNZ the Mashona mole-rat saved 21% of its energetic expense in pairs due to social thermoregulation. With an increase in group size, energetic savings rose up to four animals. In larger groups, social thermoregulation did not influence the energetic expenditure, possibly because Mashona mole-rat´s families naturally contain around four to five adults.

The thesis deals with speciation processes, thermal ecology and habitat use in Holarctic mountain and arctic butterflies. It demonstrates a crucial role of environmental heterogeneity for speciation, survival of butterfly lineages, coexistence of closely related species and, finally, for resource use of sexes with different habitats demands at the level of individual species.

abstract: Many animals thermoregulate to maximize performance. However, interactions with other animals, such as competitors or predators, limit access to preferred microclimates. For instance, an animal may thermoregulate poorly when fighting rivals or avoiding predators. However, the distribution of thermal resources should influence how animals perceive and respond to risk. When thermal resources are concentrated in space, individuals compete for access, which presumably reduces the thermoregulatory performance while making their location more predictable to predators. Conversely, when thermal resources are dispersed, several individuals can thermoregulate effectively without occupying the same area. Nevertheless, interactions with competitors or predators impose a potent stress, often resulting in both behavioral and physiological changes that influence thermoregulation. To assess the costs of intraspecific competition and predation risk during thermoregulation, I measured thermoregulation, movement, and hormones of male lizards (Sceloporus jarrovi) in experiment landscapes, with clumped to patchy distributions of microclimates. I found lizards aggressively competed for access to microclimates, with larger males gaining priority access when thermal resources were aggregated. Competition reduced thermoregulatory performance, increased movements, and elevated plasma corticosterone in large and small males. However, the magnitude of these responses decreased as the patchiness of the thermal environment increased. Similarly, under simulated predation risk, lizards reduced thermoregulatory performance, decreased movements, and elevated plasma corticosterone. Again, with the magnitude of these responses decreased with increasing thermal patchiness. Interestingly, even without competitors or predators, lizards in clumped arenas moved greater distances and circulated more corticosterone than did lizards in patchy arenas, indicating the thermal quality of the thermal landscape affected the energetic demands on lizards. Thus, biologists should consider species interactions and spatial structure when modeling impacts of climate change on thermoregulation. / Dissertation/Thesis / Doctoral Dissertation Biology 2017

INTRODUÇÃO: O excesso de adiposidade é considerado um fator que prejudica a termorregulação durante exercício no calor; entretanto, isso não tem sido observado em alguns estudos que compararam adolescentes obesos e magros. Tal diferença entre estudos pode ser devida à falta de controle de fatores tanto individuais, como nível de condicionamento aeróbico, quanto metodológicos, como nível de hidratação e produção de calor metabólico. OBJETIVO: Testar a hipótese de que meninos obesos com condicionamento aeróbico e grau de hidratação similares aos de magros, apresentam prejuízos nas respostas termorregulatórias ou perceptivas ao se exercitarem num mesmo %VO2pico ou com mesma produção de calor metabólico. MÉTODOS: Foram recrutados para este estudo 50 meninos púberes, sendo quatro desses excluídos por critérios de sobrepeso. No total, 46 (23 obesos e 23 magros), aclimatizados ao calor e com similar VO2pico por massa muscular, participaram do protocolo experimental. Entre esses, 41 meninos foram categorizados de acordo com seu condicionamento aeróbico: 20 (10 obesos e 10 magros) apresentavam alto condicionamento – “highfit” (HIfit); e 21 (10 obesos e 11 magros), baixo condicionamento – “lowfit” (LOfit). Todos pedalaram por dois períodos de 25 min, separados por 10 min de intervalo, dentro de uma câmara ambiental (35°C, 40-45% de umidade relativa), em duas sessões diferentes apenas quanto ao alvo de intensidade do exercício: 1) intensidade relativa (IR) a 40-45% do VO2pico; e 2) produção de calor metabólico fixada (PCMF) em 5,5 W.kg-1. A temperatura retal (Tretal), a temperatura da pele (Tpele) e a frequência cardíaca (FC) foram avaliadas continuamente, e variáveis perceptivas (de esforço, sensação térmica e conforto térmico) foram registradas a cada 5 min. A massa corporal foi medida antes e após cada 25 min de exercício para calcular o balanço hídrico e o volume de suor. Os meninos mantiveram-se hidratados, ingerindo, no intervalo de 10 min, um volume de água semelhante às perdas de suor decorrentes dos primeiros 25 min de exercício. RESULTADOS: O aumento na Tretal até o final do exercício foi discreto e similar entre obesos e magros, mesmo quando os grupos foram categorizados em HIfit e LOfit. Tal similaridade foi observada também no aumento da Tpele entre os grupos. No geral, a FC foi maior nos obesos em alguns momentos da sessão IR e ao longo de quase todo o exercício da sessão PCMF. Mas, quando categorizados pelo condicionamento aeróbico, foi maior em OB-LOfit vs. magros (HIfit e LOfit) no minuto 40 da sessão IR, e maior em OB-LOfit vs. MA-HIfit no minuto 50 da sessão PCMF. Entretanto, isso não foi acompanhado pela percepção de esforço nas duas sessões de exercício, nem mesmo pela sensação de calor ou desconforto térmico. CONCLUSÃO: Quando o alvo de intensidade para o exercício foi fixado pela PCM ou relativo ao VO2pico, e a hidratação foi controlada, nenhuma desvantagem termorregulatória ou de percepção ao calor foi observada por parte dos obesos, independentemente do seu condicionamento aeróbico. / INTRODUCTION: Excess adiposity is considered a factor which impairs thermoregulation during exercise in the heat. However, in adolescents, previous studies showed either similar or greater increase in rectal temperature (Tre) in obese compared to lean while exercising in the heat. The differences amongst studies may be due to lack of controlling factors such as metabolic heat production (Hprod), aerobic fitness and hydration levels. PURPOSE: To test the hypothesis that obese compared to lean adolescent boys with similar aerobic fitness and hydration levels will have greater Tre increase when exercising in the heat in a given Hprod. METHODS: Fifty pubertal boys were recruited for this study; four of these were excluded because overweight criteria; and a total of 46 (23 obese e 23 lean pubertal), heat-acclimatized, and with similar VO2peak by total muscle mass, participated in the experimental protocol. Among these, 41 boys were categorized according to their aerobic fitness: 20 (10 obese e 10 lean) were high fit (HIfit), and 21 (10 obese e 11 lean) were low fit (LOfit). All performed two 25-min exercise bouts, separated by 10-min rest in a controlled hot environment (35°C, 40-45% RH), in two sessions which only differed as the exercise intensity target: 1) relative intensity (RI) 40-45%VO2peak; and 2) metabolic heat production fixed (HProd) of 5.5 W.kg-1. Tre, skin temperature (Tskin) and heart rate (HR) were evaluated continuously, and perceptual variables (thermal sensation and thermal comfort) were recorded every 5 min. Body mass was measured before and after each exercise bout to calculate water balance and sweat volume. Boys kept hydrated as water volume intake at rest (between bouts) was similar to sweat losses from the 1st bout. RESULTS: The increase in Tre was discreet and similar between obese and lean boys at the end of exercise, even when the groups were categorized as HIfit and LOfit. It was also observed to Tskin increase. Overall, HR was higher in obese at times of the RI session, and for almost the entire Hprod session. But, when categorized by VO2peak, HR was higher in obese LOfit vs. lean (HIfit and LOfit) in the RI session (in 40th min) and higher in obese LOfit vs. lean HIfit in the Hprod session (in 50th min). However, this was not accompanied by the perception of effort in two exercise sessions, not even by the heat sensation or thermal discomfort. CONCLUSION: When the intensity target of exercising was fixed to Hprod or relative to VO2peak and hydration was controlled, as well as fitness level, no difference was found in the increase in Tre or sweat volume between groups. Therefore, our hypothesis was not verified, because no disadvantage in thermoregulatory or heat perception was observed in the obese group, regardless of aerobic fitness.

As abelhas sociais são classificadas como animais heterotérmicos, ou seja, podem ser endotérmicas ectotérmicas de acordo com a necessidade do ninho ou do indivíduo. As abelhas sem ferrão eram conhecidas por apresentarem uma termorregulação passiva, onde o invólucro, seria o responsável pela manutenção da temperatura na área de cria. Entretanto, acreditava-se em uma produção de calor ativo como apresentado em abelhas Apis mellifera, embora nunca tenha sido estudado. O objetivo principal do presente trabalho foi verificar a produção de calor ativo por meio das operárias adultas e da cria e relacionar essa produção de calor com a termorregulação passiva e o consumo de oxigênio. Foram utilizadas colônias de abelhas sem ferrão Melipona scutellaris, Frieseomelitta varia e Plebeia droryana mantidas em laboratório. Os resultados obtidos mostraram que a temperatura na área de cria foi sempre maior que na periferia do ninho. Foi verificado que os imaturos produzem calor metabólico e que o invólucro é o responsável pelo isolamento do calor produzido. Além disso, as operárias presentes nas áreas de cria apresentaram temperaturas superficiais torácicas elevadas, sugerindo um incremento na produção de calor na área de cria. Foi observado que as abelhas consomem menos oxigênio quando estão em grupo do que individualmente, sugerindo uma cooperação entre as abelhas ou uma redução de stress em grupo entre as abelhas que pode estar relacionada com a termorregulação colonial. Este trabalho traz novas possibilidades para os estudos de termorregulação, pois confirma a produção de calor ativo em abelhas sem ferrão, até no momento desconhecido / Social bees are classified as heterothermic animals, may be both endothermic and ectothermic according to the necessity of the colony or the individual. The stingless bees are known because the passive thermoregulation, which the involucrum would be responsible for maintenance of the brood area temperature. However, it has been believed in an active heat production as shown in honeybees, although it not studied so far. The aim of the present study was to verify the active heat production through adult workers and brood, and to correlate the heat production with the passive thermoregulation and the oxygen consumption. We used colonies of stingless bees Melipona scutellaris, Frieseomelitta varia and Plebeia droryana maintained in laboratory. Our results showed that the brood area temperature was higher than the nest periphery temperature. We also verified that the immature produces metabolic heat, and that the involucrum is responsible by the isolation of the produced heat. Furthermore, the workers engaged on the brood area had their thoracic surface temperatures higher than other workers, which suggest the increasing of the heat production in the brood area. Bees consumed less oxygen in group than when they are individually tested. This study brings new possibilities to the thermoregulation studies, because it confirms the active heat production in stingless bees

O objetivo deste estudo foi avaliar a tolerância ao calor de ovinos de corte das raças Santa Inês, Dorper e Merino Branco através do teste de capacidade termolítica (exposição ao sol). Foram utilizadas um total de 97 fêmeas vazias, com idade média de 3 anos. O estudo decorreu no verão, onde foram registradas as variáveis fisiológicas temperatura retal (TR), temperatura superficial (TS), frequência respiratória (FR), mensuradas depois de duas horas sob a sombra (1), uma hora sob o sol (2), quinze (3) e trinta (4) minutos após a exposição ao sol, e a taxa de sudação (Sud), no tempo 2. Posteriormente foram realizadas observações de comportamento a pasto durante três dias, no período das 11 às 14 horas, para as variáveis: tempo ao sol; tempo em pé; pastejo/alimentação, ruminação e ócio. As médias de TR1 foram semelhantes para as ovelhas Santa Inês e Dorper e superior para as ovelhas Merino Branco (P<0,05). Para TR2, TR3 e TR4 as ovelhas da raça Merino Branco tiveram os maiores valores, seguidos das ovelhas da raça Santa Inês e com os menores aumentos de temperatura retal nas ovelhas da raça Dorper (P<0,05). Estes resultados refletiram na capacidade termolítica individual, sendo menor para a raça Santa Inês (P<0,05). Após exposição ao sol observaram-se diferenças entre as TS, sendo as da raça Merino Branco mais elevadas, seguidas pelas da raça Dorper e da Santa Inês (P<0,05). A raça Merino Branco apresentou as maiores FR, seguida das raças Dorper e Santa Inês, todas diferentes entre si (P<0,05). Todos os animais expostos por uma hora ao sol apresentaram aumento nas TR, TS e FR (P<0,05), e se aproximaram dos níveis encontrados antes da exposição ao sol após trinta minutos de descanso sob a sombra (Santa Inês e Dorper P<0,05; Merino Branco P>0,05). A taxa média de sudação para as ovelhas da raça Santa Inês foi superior a encontrada para as ovelhas da raça Dorper (P<0,05). Houve diferença entre os animais dentro de cada raça (P<0,05), confirmando a hipótese de grande variabilidade entre os indivíduos e diferenças entre as raças. Com relação ao comportamento, as ovelhas da raça Santa Inês continuaram em pastejo mesmo nas horas mais quentes do dia, tendo sido encontrada uma correlação positiva de 0,64 entre a capacidade termolítica individual e o pastejo ao sol, enquanto as ovelhas da raça Dorper preferencialmente permaneceram à sombra devido ao manejo semiconfinado. No presente trabalho o tipo de manejo alimentar influenciou no tempo de uso da sombra. Sob as condições climáticas encontradas no experimento os animais estudados tiveram seus parâmetros fisiológicos alterados devido à exposição ao sol, e os animais das raças Dorper e Merino Branco mostraram maior capacidade termolítica do que os animais da raça Santa Inês, sendo este um fator que pode influenciar na tolerância ao calor individual. / The aim of this study was to evaluate the heat tolerance of three meat sheep breeds, Santa Ines, Dorper and White Merino using Thermolysis capacity test. 97 non pregnant females (3 years old) were used in the study that took place in the summer. Physiological variables as rectal temperature (RT), surface temperature (ST), respiratory rate (RR) were measured after two hours under the shade (1), after one hour under the sun (2), fifteen (3) and thirty (4) minutes after sun exposure, and sweating rate (SR) on time 2. Were also collected behavioral data during three days in the period from 11:00 to 14:00 hours: say in the sun, standing posture, eating, ruminating and idling. RT1 means were equal Santa Ines and Dorper, and greater for White Merino (P<0.05). White Merino also had greater values for RT2, RT3 e RT4, followed by Santa Ines and Dorper (P<0.05). These results reflected the thermolysis capacity, being lower for Santa Ines breed (P<0.05). After sun exposure differences between ST were observed, and greater values were found for White Merino, followed by Dorper and Santa Ines breeds (P<0.05). In the same way, White Merino had the highest RR, followed by Dorper, which had higher RR compared to Santa Ines (P<0.05). All animals exposed to the sun for an hour showed increased RT, ST, RR values (P<0.05), and approached the levels found before exposure to the sun after thirty minutes of rest in the shade (Santa Ines and Dorper P<0.05; White Merino P>0.05). Sweating rate for Santa Ines breed was higher than those found for Dorper breed (P<0.05). There were differences among animals within each race (P<0.05), confirming the hypothesis of great variability among individuals and differences between the breeds. With respect to behavior, Santa Ines ewe grazed even during the hottest hours of the day, and a positive correlation of 0.64 between the individual thermolysis capacity and grazing in the sun was found, while the Dorper ewes remained preferentially under the shade due to the semi-confined management. In the present study, feedin management influenced the time under the shade. Under experimental climatic conditions, the studied ewes had theirs physiological parameters increased due to sun exposure, and Dorper and White Merino breeds showed a greater thermolisys capacity than the animals of the Santa Ines breed, which is a factor that can influence individual heat tolerance.