Browsing by Author "Dial, Elizabeth Jane Samson"
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Item Relationship between brain norepinephrine and barbital activity in stressed and nonstressed rats(1972) Dial, Elizabeth Jane Samson; Clay, Michael M.; Euler, Kenneth L.; Cominsky, N. CatherineChronic and acute stress is known to affect barbiturate activity. The effects of 14 day restriction-of-movement stress and hindleg ligation stress, singly and in combination, were observed on the duration of hypnosis of barbital (200 mg/kg, I.P.). Tolerance to barbital was observed when it was administered beginning at 26, 50, 74 hours after removal from chronic stress(without acute stress, however, it was significant only in males). Administration of acute stress at 50 hours after removal from chronic stress resulted in elimination of tolerance to barbital. A subsequent injection 24 hours later produced tolerance to barbital, Proadifen (50 mg/kg, IP) prolonged sleeping time with the second dose of barbital, but had no effect on the first dose in chronically and acutely stressed animals. Proadifen did lengthen sleeping time when the first dose of barbital was administered 50 hours after stress in chronically stressed rats. The stress changes in barbital activity were studied by determination of the whole brain norepinephrine concentration. Chronic stress resulted in a greater brain concentration of norepinephrine than that seen in non-stressed rats. Barbital hypnosis increased the brain norepinephrine concentration in non-stressed rats, but not in stressed rats, stressed animals exhibited a shorter sleeping time than non-stressed animals.Item Studies on rat cardiovascular monoamine oxidase activity(1978) Dial, Elizabeth Jane Samson; Clarke, David E.; Hazelwood, Robert L.; Mailman, David S.; Wagner, Lorin A.; Buckley, Joseph P.Studies were performed to determine the characteristics of rat cardiac monoamine oxidase (MAO) activity. Rat major blood vessels were also examined, since the coronary vasculature constitutes a significant portion of cardiac tissue. MAO is known to exist in two types, A and B, as determined by the inhibitor clorgyline. However, rat heart MAO is claimed to differ radically from that found in other tissues and a multiplicity of MAO activities within the A and B types has been postulated. Thus, a comparison was made between rat heart MAO with that of the rat vas deferens and human cardiovascular tissues. Rat cardiac and vas deferens MAO activity revealed no major differences regarding apparent Km values, inhibitor sensitivity (with the exception of pargyline), or mixed substrate interactions using kynuramine as the substrate. However, rat major blood vessels contained MAO activities which varied in substrate and inhibitor selectivity. While the rat heart had predominantly type A activity, the blood vessels contained type A and a cl orgy 1 ine-resistant species. In contrast, the rat vas deferens had approximately equal amounts of A and B activity. The large A:B ratio in the rat heart explains why many MAO substrates are metabolized only by type A in that organ. [...]