Urethane anesthetized guinea pigs exhibit a decrease in heart rate (HR) upon i.v. injection of substance P (SP). The purpose of this project was to determine if this effect is due to cholinergic stimulation by SP. Male Hartley guinea pigs (400-650g) were anesthetized with urethane (1.5 g/kg, i.p.) and bilaterally vagotomized. Blood pressure was recorded by cannulation of the left carotid artery. Heart rate (HR) was derived from the pressure signal. The trachea was cannulated to allow for artificial respiration. SP, saline and other drugs were injected (50 μl bolus) through a cannula in the left jugular vein. SP (32 nmol/kg) produced a brief bradycardia and prolonged hypotensive response under these conditions. After control responses to SP, animals were either given a muscarinic antagonist (atropine) or a cholinesterase inhibitor (physostigmine). The bradycardia evoked by the second injection of SP was attenuated by atropine (1 μmol/kg; n=5, P=0.041) and augmented by physostigmine (0.9 μmol/kg; n=5, P=0.050). These results suggest that the negative chronotropic response to SP is mediated by cholinergic neurons.

Previous work demonstrated that SP causes bradycardia in isolated guinea pig hearts by stimulating cholinergic neurons. The present study was initiated to determine if SP could evoke bradycardia in vivo and affect the chronotropic response to vagal stimulation (VS). Male Hartley guinea pigs were treated with reserpine (5 mg/kg, i.p.) to deplete norepinephrine and neuropeptide Y from sympathetic nerves. After 24 h, they were anesthetized with urethane (1.5 g/kg, i.p.) for measurement of blood pressure and heart rate. Both vagal nerves were cut and animals artificially respired. Saline or SP was given by bolus i.v. injection in a volume of 50 1. SP (3.3-33 nmol) caused a dose-dependent bradycardia that was sometimes followed by a slight tachycardia. It also evoked a prolonged decrease in blood pressure. The right vagus was stimulated at l min intervals to cause bradycardia of about 20 to 40 beats per min. Saline had no effect on the response to VS. Effects of SP and VS on heart rate were initially additive or synergistic. The bradycardia evoked by the second VS after injection of SP was less than that to the first and frequently less than pre-SP control values. Responses subsequently returned to the pre-SP control level within two trials or increased above this level for several trails before returning to baseline. These observations support the concept that endogenous tachykinins may have important effects on neurotransmission in the intrinsic cardiac ganglia.

To study possible interactions between dopamine (DA) and serotonin (5-HT) neurochemical systems in the D-1 supersensitized induction of oral activity in neonatal 6-hydroxydopamine (6-OHDA) lesioned rats, the effects of a series of 5-HT agonists and antagonists were determined. At 3 days after birth rats were treated with desipramine HCl (20 mg/kg i.p., base form, 1 hr) and 6-OHDA HBr (100 μg, salt form, in each lateral ventricle). Rats were observed individually as adults, once a minute every 10 min over a 1-hr period after challenge with a DA or 5-HT receptor agonist. The respective 5-HT(1A) and 5- HT(1B) agonists, (±)-8-hydroxydipropylaminotetralin (0.50 mg/kg s.c.) and CGS 12066B maleate (7-trifluoromethyl-4(4-methyl-1-piperazinyl)-pyrrolo[1,2- alquinoxaline], 1:2 maleate salt; 3.0 mg/kg i.p.), did not increase oral activity. The mixed 5-HT(1C) and 5-HT2 receptor agonist, m- chlorophenylpiperazine (m-CPP), produced a slight increase in oral activity in control rats and a marked increase in oral activity in 6-OHDA-lesioned rats. In the 6-OHDA group the peak effect of 76.5 ± 4.1 oral movements occurred with an m-CPP 2-HCl dose of 4.0 mg/kg. Pindolol (1.0 mg/kg i.p.), ketanserin tartrate (5 mg/kg i.p.) and MDL-72222 (3-tropanyl-3,5- dichlorobenzoate; 10 mg/kg s.c.), antagonists with high affinity for 5- HT(1A,1B), 5-HT2 and 5-HT3 receptors, respectively, did not attenuate m-CPP actions. However, mianserin HCl (1.0 mg/kg s.c.), an antagonist with high affinity for 5-HT(1C) and 5-HT2 receptors, attenuated the oral response to m-CPP. Although the supersensitized oral response of neonatal 6-OHDA-lesioned rats to m-CPP was not attenuated by the DA D-1 receptor antagonist, SCH 23390 HCl [R-(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3- benzazepine hydrochloride; 0.30 mg/kg i.p.], the enhanced response of the D-1 agonist, SKF 38393 HCl [(±)-1-phenyl-2,3,4,5-tetrahydro-(1H)-3-benzazepine- 7,8-diol hydrochloride; 1.0 mg/kg i.p.], was attenuated by mianserin (1.0 mg/kg i.p.). Striatal DA content was reduced by 98.6%, whereas 5-HT content was elevated by 77% in the 6-OHDA group. These findings demonstrate that neonatal 6-OHDA destruction of central DA-containing neurons is associated with supersensitized 5-HT receptors, probably of the 5-HT(1C)subtype. Moreover, induction of oral activity by DA agonists is mediated via a serotoninergic system.

Negative chronotropic and vasodilator responses of the isolated perfused guinea pig heart to substance P (SP) were evaluated. Bolus injections of 2.5, 25 and 125 nmol of SP caused a dose-dependent bradycardia, with the largest dose decreasing heart rate by 53% of base line. Pretreatment with 1 μM atropine blocked the negative chronotropic response to 25 nmol of SP. Pretreatment with 0.5 μM neostigmine lowered base-line heart rate and potentiated the negative chronotropic response to 25 nmol of SP. A potent vasodilator response to SP was demonstrated after elevation of base-line perfusion pressure with 1 μM [Arg8]vasopressin or 40 mM KCl. The vasodilator effect of SP was dose-dependent and occurred at much lower doses than required to affect heart rate. The ED50 for vasodilation was less than 1 pmol in both preparations. In hearts with vascular tone increased by vasopressin, atropine (1 μM) decreased the maximum vasodilator response to SP by 23%, but neither atropine nor a combination of 10 μM cimetidine and 1 μM chlorpheniramine affected the ED50 for SP. These results suggest that SP causes bradycardia by stimulating cholinergic neurons and coronary vasodilation by some mechanism not involving either acetylcholine or histamine. Acetylcholine may, however, contribute to the maximum vasodilator response to SP.

This project tested the hypothesis that inhaled oxidants could cause lung damage by inactivating the proteinase inhibitors that normally protect the lung from proteolysis. Rat alpha-1-proteinase inhibitor (alpha 1-PI)2 was purified from blood plasma, and antibodies to this inhibitor were prepared. The activity of alpha 1-PI in lung lavage fluids from rats was measured by elastase inhibition, and the immunological concentration of alpha 1-PI was quantified in an enzyme-linked immunoassay. The ratio of the amount of active alpha 1-PI relative to its immunological concentration was examined as a measure of the inhibitor's functional activity. This ratio and the ratio of the immunological concentration of alpha 1-PI to the total protein concentration were determined in lung lavage fluids from rats exposed to air, 10 parts per million (ppm) nitrogen dioxide, and diesel emissions (3.5 mg/m3 particulates) for 12, 18, and 24 months. Only diesel exposures resulted in a statistically significant reduction in the functional activity of alpha 1-PI of 30 percent (p less than 0.05). Similar studies were performed on rats exposed to nitrogen dioxide (0.5 ppm background with peaks of 1.5 ppm) and ozone (0.06 ppm background with peaks of 0.25 ppm) for 12 and 18 months. No statistically significant effects were observed in the functional activity of alpha 1-PI or its immunological concentration. In other protocols, rats were acutely exposed to 0.8 ppm or 1.2 ppm ozone for two, four, or eight hours, and to 0.5 ppm or 0.8 ppm ozone in conjunction with 8 percent carbon dioxide for two or seven hours. Although these acute exposure conditions did not reduce the functional activity of alpha 1-PI, the immunological concentration of alpha 1-PI and the elastase inhibitory activity, relative to other proteins, were significantly increased in relation to the total amount of ozone inhaled. The functional activity of alpha 1-PI also was measured in the bronchoalveolar lavage fluids of human subjects exposed to nitrogen dioxide (0.05 ppm with 2 ppm peaks, or to 1.5 ppm continuously) for three hours and to ozone (0.4 ppm) for two hours during exercise. These exposures did not result in significant changes in the functional activity of alpha 1-PI or its immunological concentration.(ABSTRACT TRUNCATED AT 400 WORDS)

No description available.

Intact chromosomal DNAs are routinely prepared by embedding cells in agarose plugs before lysis. The large sizes of the genomic DNAs cause their retention while other macromolecules diffuse into and out of the gel matrix during lysis, washing and restriction cleavage incubations. However, in an analysis of agarose-embedded chromosomal DNAs cleaved with restriction enzymes, fragments larger than 30 kilobases were found to have eluted from the gel plugs. Since loss of fragments from gel plugs may affect qualitative and quantitative interpretations of electrophoretic patterns, an analysis of the diffusion of DNA segments from agarose plugs was performed. The two variables monitored were the time dependence and the DNA fragment size dependence of the diffusion process. The results indicate that small fragments (≤2 kilobases) are quickly lost from 1% agarose gel plugs; moreover, significant amounts of large DNA segments (i.e., the 48.5-kilobase lambda phage chromosome) are also lost. In addition to urging caution in the analysis of restriction cleavage data, these observations suggest that intact small organelle genomes and extrachromosomal DNAs also may be lost from genomic DNAs prepared in agarose gel plugs.

No description available.

No description available.

The ultrastructure of the surface epithelium and the associated basal lamina of the gill arches of the striped bass, Morone saxatilis, were investigated with the scanning electron microscope following complete or partial removal of the epithelium by ultrasonic microdissection. The microdissection procedures employed various combinations of the techniques of aldehyde fixation, treatment with borate, and extensive osmication followed by mild sonication. Generally, aldehyde fixation increases intercellular adhesion, excess osmication increases tissues brittleness, and borate treatment causes extensive tissue dissociation. However, the degree of epithelial removal following sonication of tissues treated with these various procedures varies considerably with specimen structure, shape, proximity to adjacent structures and freedom to vibrate during sonication. The basal lamina exhibits a smooth contour over most of the gill surface with the exception of the short gill rakers where it formed cones within the taste bud cores, and on the respiratory lamellae where it closely mimicked the underlying capillary network.