Effects of electrical stimulation on the efflux of L-glutamate from peripheral nerve in vitro.
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Biomedical subjects
Publications and source records attributed to F V DeFeudis.
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Recent results support the hypothesis that microglia and/or macrophages of the brain, by producing oxidants, could play a role in the local inactivation of the Kunitz protease inhibitor (KPI) domain of beta-amyloid precursor protein (APP), thereby facilitating deposition of abnormal amyloid filaments in patients with Alzheimer's disease (AD). Protease inhibitors and/or free radical scavengers might serve as therapy for the amyloidosis of AD.
Taking their lead from studies which have shown that endothelium-derived relaxing factor(s) (EDRF) mediates vasorelaxation by activating smooth muscle guanyl cyclase, the authors of the current article have examined the role of the endothelium in relation to the effects of the alpha-adrenoceptor antagonist prazosin. Prazosin acted as a non-competitive antagonist of norepinephrine- (NE-) induced contraction in rat aortic preparations with intact endothelium, but as a competitive antagonist in endothelium-denuded preparations. The affinity of NE for its smooth muscle receptor was the same in the presence or absence of endothelium, but its efficacy was 7 times lower in the presence than in the absence of endothelium. Other experiments showed that inhibition of guanyl cyclase by methylene blue in the presence of endothelium (like endothelium removal) led to competitive antagonism of NE responses by prazosin, and that increasing the tissue content of cyclic GMP by pre-incubating de-endothelialized preparations with 8-Br-cyclic GMP (as in intact preparations) led to non-competitive antagonism of NE responses by prazosin. The authors concluded that EDRF, by increasing the cyclic GMP content of vascular smooth muscle of rat aorta, can modify the efficacy of NE, and thereby alter the mode of antagonism of prazosin.