Biomedical subjects

J H Chamberlain

Publications and source records attributed to J H Chamberlain.

36 records · Page 2Linked to original sources

PubMed1977

Behavioral comparisons of R-2-amino-1-(2,5-dimethoxy-4-methylphenyl) butane (BL-3912A) with R-DOM and S-amphetamine.

The behavioral effects of R-2-amino-1-(2,5-dimethoxy-4-methylphenyl) butane or BL-3912A were compared with those of S-Amphetamine and R-DOM. BL-3912A facilitated acquisition of shuttle box responding by rats without increasing noncontingent intertrial (ITI) activity, while S-Amphetamine increased both avoidance and ITI responding. R-DOM had a biphasic effect on avoidance responding, increasing it at low doses and disrupting at higher doses. At doses that facilitated shuttle box responding, BL-3912A had no effect on unacclimated motor activity of rats nor on the rate of continuous avoidance responding by rats. S-Amphetamine increased the frequency of both motor activity and operant avoidance responding, while R-DOM decreased motor activity and increased operant avoidance responding. By facilitating avoidance behavior without increasing othermeasures of psychomotor activity, BL-3912A represents a unique psychopharmacological agent clearly different from R-DOM and S-Amphetamine.

DOM 2,5-Dimethoxy-4-Methylamphetamine↗

PubMed1977

Further studies on BL-3912A: effects on avoidance behavior of rats with low baselines and on reaction thresholds to electric footshock.

Rats selected for their low performance baselines in an active avoidance shuttle box task were given various doses of R-(-)-2-amino-1-(2,5-dimethoxy-4-methylphenyl) butane (BL-3912A), S-amphetamine or piracetam. BL-3912A at 1 mg/kg IP had no significant behavioral effects, while 5 and 10 mg/kg significantly increased the number of avoidance responses without affecting responses during the intertrial interval (ITI). Statistically reliable effects on behavior were not observed following 20 mg/kg of BL-3912A. S-Amphetamine at 0.5 and 1 mg/kg IP also facilitated avoidance responding, but could be differentiated from BL-3912A in that the S-amphetamine significantly increased shuttles during the ITI. S-Amphetamine at 0.1 mg/kg was not effective, while 2 mg/kg increased ITI activity. Piracetam (50 or 200 mg/kg) had no significant effects on avoidance or shuttles during ITI. Using an electric shock titration procedure, BL-3912A at 10 and 20 mg/kg IP had no significant effect on reaction thresholds. Animals receiving 100 mg/kg of p-chlorophenylalanine po for 3 days and tested 2 days later showed hyperalgesia to the electric shock. In summary, BL-3912A facilitated shuttle box avoidance responding of rats with low performance baselines. Behavioral facilitation occurred without concomitant increases in noncontingent activity or apparent changes in reactivity to electric footshock.

DOM 2,5-Dimethoxy-4-Methylamphetamine↗

PubMed1977

Myocardial stimulation by pancuronium bromide.

The effect of pancuronium bromide on the canine myocardium was studied by observing several indices of myocardial contractility during i.v. and intracoronary infusion of the drug in an anaesthetized, open-chested dog preparation. Pancuronium produced tachycardia when given for 2 min by i.v. and intracoronary infusion with the heart intact. Following denervation and pacing of the heart the intracoronary infusion of the drug produced increases in maximum acceleration of blood at the aortic root, peak aortic blood flow, maximum dP/dt and (maximum dP/dt)/TP. These changes occurred about 30 s after starting the infusion and returned to control values 5 min after stopping the infusion.

Animals↗

PubMed1977

Effect of thiopentone on myocardial function.

In a canine preparation designed to separate myocardial from peripheral cardiovascular effects of the drug. It was found that thiopentone produced minimal depression of the heart. Only in much greater concentrations was significant depression found. It is concluded that the cardiovascular effects of thiopentone i.v. are not a direct effect on the heart.

Animals↗

PubMed1975

Behavioral and neuropharmacological analysis of amphetamine and 2,5-dimethoxy-4-methylamphetamine in rats.

A comparison of the behavioral pharmacology of DOM and amphetamine in rats indicated that lower doses (0.10-1.0 mg/kg) of the two agents had similar effects on schedule-controlled food-reinforced and shock-avoidance behavior. Similarities were also noted in their effects on horizontally directed motor activity when testing was preceeded by a period of acclimation. However, most doses of DOM tended to decrease unacclimated motor activity, while amphetamine increased this behavior. Neuropharmacological antagonism studies indicated that brain catecholamines (CA) and serotonin (5-HT) are involved in the behavioral effects of both DOM and amphetamine. Cinanserin, a 5-HT receptor blocker, attenuated the behavioral disruptive effects of both agents on food-reinforced responding. Cinanserin attenuated the effects of all doses of DOM and those of higher doses of amphetamine on shock avoidance. When given prior to lower doses of amphetamine, there was a greater behavioral stimulation than when amphetamine was given alone. Prior depletion of brain CA with alpha-methyltyrosine (alpha-MT) did not affect DOM induced disruption of food-reinforced responding, while alpha-MT attenuated the behavioral effects of all doses of DOM and amphetamine on shock avoidance. These data suggest that DOM and amphetamine share a similar component in their mechanism of action which depends on the availability of a releasable pool of brain CA.

DOM 2,5-Dimethoxy-4-Methylamphetamine↗

PubMed1975

Cardiac output measurement by indicator dilution.

The measurement of cardiac output by the indicator dilution method is reviewed. Theoretical and practical problems relating to the direct and indirect Fick methods and the continuous and bolus injection methods are considered in detail. Choice of indicator is also discussed. Problems remain with all of these methods, but reasonable accuracy and consistency may be achieved if attention is paid to detail.

Cardiac Output↗

PubMed1974