| Co-Investigator(Kenkyū-buntansha) |
FUJIOKA Hideyuki Shiga University of Medical Science, Pharmacology, Research Associate, 医学部, 助手 (50228970)
AYAJIKI Kazuhide Shiga University of Medical Science, Pharmacology, Associate Professor, 医学部, 助教授 (10167968)
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| Research Abstract |
The aims of this study are to determine the projection route of nitroxidergic (nitrergic) nerves which innervate blood vessels and corpus cavernosum and dilate their smooth muscles, and to analyze their transmission mechanism. Summary of the study is as follows.
1. Postganglionic neurons from the pterygopalatine ganglion play crucial roles in cerebral and ophthalmic vasodilation mediated by NO from the nerve, arid preganglionic neurons, possibly from the superior salivatory nucleus through the greater superficial petrosal nerve, innervate the pterygopalatine ganglion in monkeys and dogs. Tonic discharges from the vasomotor center participate significantly in the maintenance of cerebal and ophthalmic vasodilation.
2. Nitroxidergic (nitrergic) nerves innervating porcine cerebral arteries liberate NO, but not stable products of NO, on excitation as a neurotransmitter to produce muscle relaxation, and the nerve function is protected by endogenous SOD from degradation of NO by superoxide anions.
3. Hypoxia-induced impairment of the function of nitroxidergic (nitrergic) vasodilator nerve innervating dog middle cerebral arteries is prevented by cooling, which may partially explain the effecacy of hypothermia in protecting against ischemic neuronal injury in the brain.
4.Neurogenic relaxation of canine corpus cavernosum is mediated by NO synthesized from L-arginine in nerve terminals, and this nerve is originated from ganglia located close to the corpus cavernosum but not directly from the pelvic nerve plexus.
5. N-type, but not L-type, calcium channels are responsible for increasing cytosolic free calcium, a prerequisite for the synthesis of NO, in the nitroxidergic (nitrergic) dilator nerves innervating the corpus cavernosum.
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