Source: Dissertation Abstracts International, Volume: 40-06, Section: B, page: 2552. / Thesis (Ph.D.)--The Florida State University, 1979.

This dissertation project represents an investigation of the regulation of glycolysis during contractile activity in the phasic adductor muscle of the bay scallop Argopecten irradians concentricus. Changes in intracellular pH during the course of 200 electrically stimulated contractions were monitored using ('31)P-NMR. There was an initial increase (from 7.06 to 7.15) followed by a gradual decrease in intracellular pH. Intracellular pH dropped to 6.94 after 200 contractions. The pattern of changes in intracellular pH was closely correlated with the pattern of proton yield from metabolic energy transformations. Changes in the concentrations of glycolytic intermediates during the course of contractile activity were measured in order to identify the potential regulatory sites of glycolysis. The estimated mass action ratios at resting conditions and after contraction, as well as the maximum activities of glycolytic enzymes, indicated that phosphorylase and phosphofructokinase were catalyzing non-equilibrium reactions in the muscle. Regulation of the terminal dehydrogenase in glycolysis, namely octopine dehydrogenase, was investigated by studying the kinetic properties of the purified enzyme. It was concluded that pyruvate was the decisive factor in activating octopine dehydrogenase. Activities of both phosphorylase and phosphofructokinase increased during muscle contraction. Phosphofructokinase appeared to be the main rate limiting enzyme in the later stages of contraction. Activation of the first rate limiting enzyme in glycolysis, namely phosphorylase, was mainly by the conversion of the inactive enzyme form (phosphorylase b) to the active form (phosphorylase a). The percentage of phosphorylase a rose from 21% to 81% of total phosphorylase after 160 electrically stimulated contractions. Activation of phosphofructokinase resulted mainly from increase in / positive modulators such as AMP and fructose-2,6-P. The initial increases in intracellular pH may also result in considerable increase of the activity of phosphofructokinase. / Source: Dissertation Abstracts International, Volume: 46-12, Section: B, page: 4147. / Thesis (Ph.D.)--The Florida State University, 1985.

Six male subjects underwent two levels of sodium deprivation to determine the effects of restricted sodium intake on arterial pressure and maximum oxygen uptake. Seven days of restricted sodium intake (63 mEq/day) resulted in significant increases in plasma renin and serum sodium concentration with accompanied decreases in blood volume, urine sodium concentration and arterial pressure. Maximum oxygen uptake did not change significantly as a result of the restricted sodium intake. Further restrictions in sodium ingestion (20 mEq/day) resulted in a greater renal retention of sodium without an apparent effect on blood volume, arterial pressure or maximum oxygen uptake. Continued restriction on sodium ingestion (63 mEq/day) beyond a seven day period eventually resulted in an adaptation response in plasma renin and blood volume. Plasma renin and blood volume returned toward pre-study levels with the continued administration of low sodium while arterial pressure remained depressed. Results of the study indicate that the treatment of hypertension with diets low in sodium resulted in a significant decrease in blood volume and arterial pressure without adversely affecting maximum oxygen uptake. / Source: Dissertation Abstracts International, Volume: 46-09, Section: B, page: 2967. / Thesis (Ph.D.)--The Florida State University, 1985.

Eight members of the research diving community in Tallahassee, Florida were volunteers for this project to determine if there was an acclimation effect due to repeated cold exposures in water 18(DEGREES)C at two atmosphere of pressure absolute, three days per week for two weeks breathing air. / The divers performed three 30 minute dives per week for two weeks wearing bathing suits and diving the Kirby Morgan Band Mask (KMB). Each diver completed series of pre- and post-acclimation tests in a cold water bath at 25(DEGREES)C, which included the monitoring of mean skin and body temperatures, Vo(,2) and thermoregulator Vo(,2), and maximum tissue insulation. Each diver also had their perceived cold, post-dive finger temperatures, and time to shivering onset recorded during each of the six dives. / A significant decrease was seen in MST and MBT at the shivering threshold between the pre- and post-acclimation cold water bath exposure test and cold air exposure test. No difference was seen in the thermoregulatory Vo(,2) at the shivering threshold between the pre- and post-acclimation cold water exposure test. There was also a significant increase in time to the onset of shivering during the cold water exposure test, cold air exposure test (at 5(DEGREES)C), and during the six cold water dives. There was a decrease in the perceived cold as reported by the subjects over the six cold water dives. There, however, was no difference between the pre- and post-acclimation tissue insulation. / There was an acclimation effect from the two week diving exposure in cold water evidenced by an decrease in shivering threshold, a reduction in post-dive finger temperature, and an enhanced feeling of well being by the divers over the two week period of dives. / Source: Dissertation Abstracts International, Volume: 46-04, Section: B, page: 1078. / Thesis (Ph.D.)--The Florida State University, 1985.

Na('+)-Li('+) countertransport is apparently responsible for the fact that the concentration of Li('+) inside Li('+)-treated red blood cells is less than expected for a passive distribution. It has been suggested that a similar countertransport mechanism should be found in nervous tissue. In this study, I examined whether countertransport or the ouabain-sensitive Na('+)-K('+) pump maintains the transmembrane Li('+) gradient in Li('+)-treated olfactory nerves from garfish (Lepisosteus osseus). I also examined how phloretin changes transmembrane distributions of monovalent cations and nerve excitability. From the results, I find that Li('+) apparently is distributed nonpassively in the olfactory nerve, since the ratio of Li('+) (,i)/ Li('+) (,o) across axons is 1.5-2.1. A ratio of 10:1 expected for a passive distribution at an assumed membrane potential of -60 mV. The nonpassive gradient for Li('+) is phloretin-sensitive, ouabain-insensitive, and Na('+)-dependent. Thus, the mechanism maintaining this gradient may be an Na('+)-Li('+) countertransport similar to that postulated for RBC. Transmembrane Na('+) and K('+) gradients also decrease in solutions containing high concentrations of phloretin, probably due to a phloretin-induced increase in membrane permeability to cations. Low concentrations of phloretin (0-50 uM) decrease impulse velocity, action potential magnitude, and rheobasic threshold, and increase the membrane time constant, of the nerve. At short stimulus durations, excitation threshold in phloretin increases, and at long durations, it decreases. Comparisons of electrophysiological effects between 0-50 mM phloretin and 0-50 mM LiCl (from earlier investigations) suggests that phloretin decreases nerve excitability by decreasing membrane conductances to Na('+) and K('+), while Li('+) decreases excitability by blocking the Na('+)-K('+) pump and / decreasing transmembrane Na('+) gradients. Two major contributions of this work are the presentation of evidence for Na('+)-Li('+) countertransport in axons, and examination of the effects of phloretin on the propagated nerve impulse. / Source: Dissertation Abstracts International, Volume: 46-04, Section: B, page: 1079. / Thesis (Ph.D.)--The Florida State University, 1985.

The regulation of pituitary gonadotropin release by testicular steroids is well established and is part of the dynamic equilibrium maintained in the hypothalamo-hypophyseal-gonadal axis. A nonsteroidal testicular factor, GnS, may also contribute to the negative feedback regulation of FSH synthesis and release. The physiological role of this factor is the subject of these studies. / Since FSH contributes to normal spermatogenesis in the adult male rat, long-term suppression of serum FSH would diminish, at least quantitatively, normal spermatogenesis. Chronic administration of GnS in the form of porcine follicular fluid (pFF), significantly depresses serum FSH levels, but it also induces antibodies to the FSH-inhibiting activity. Thus, FSH suppression cannot be maintained long enough to effect changes in fertility. / Constant low levels of testosterone produced by Silastic capsules provide complete feedback control of FSH in the acute castrate. Testosterone prevents the postcastration increase in serum FSH which, in turn, prevents the early postcastration drop in pituitary FSH. Later postcastration elevations in pituitary FSH are also prevented. Although GnS suppresses serum and pituitary FSH by inhibiting release and synthesis, it is not needed in the acute castrate. / In the long-term castrate animal, testosterone alone only partially controls serum FSH while pituitary FSH levels are increased. GnS prevents the testosterone-induced accumulation of hypophyseal FSH and independently suppresses serum FSH. Thus, in the long-term castrate both testosterone and pFF are needed to suppress FSH levels. / Finally, evidence is presented that constant low levels of androgen, when administered via Silastic capsules, provide more effective feedback than the feedback provided by normal fluctuating androgen levels in the intact rat. / Source: Dissertation Abstracts International, Volume: 44-02, Section: B, page: 0423. / Thesis (Ph.D.)--The Florida State University, 1983.

Source: Dissertation Abstracts International, Volume: 31-09, Section: B, page: 5575. / Thesis (Ph.D.)--The Florida State University, 1970.

Source: Dissertation Abstracts International, Volume: 31-09, Section: B, page: 5580. / Thesis (Ph.D.)--The Florida State University, 1970.

Source: Dissertation Abstracts International, Volume: 31-09, Section: B, page: 5585. / Thesis (Ph.D.)--The Florida State University, 1970.

Source: Dissertation Abstracts International, Volume: 31-11, Section: B, page: 6867. / Thesis (Ph.D.)--The Florida State University, 1970.