SPECIFIC TENSION DEVELOPMENT AND Ca^<2+> INFLUX OF AORTA FROM SPONTANEOUSLY HYPERTENSIVE RAT
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概要
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To understand the cellular process leading hypertension, the characteristics of membrane system in vascular smooth muscle as a regulatory site for free Ca^<2+> of cytoplasma were investigated. For this purpose, the differences of contractile response and Ca^<2+> influx between isolated aorta from spontaneously hypertensive rat (SHR) and Kyoto Wistar normotensive rat (KNR) were analized. Hypertonic K^+ induced tension and slow component of 5-Hydroxytryptamine (5-HT) and noradrenaline (NA) induced tension depended on extracellular Ca^<2+>, whereas fast component of 5-HT and NA induced tension depended of intracellular Ca^<2+>. After washing the aortic strip in Ca^<2+>-free Krebs containing 5-HT to extrude intracellular Ca^<2+>, aortic strip from SHR developd significantly larger tension than that from KNR upon addition of Ca^<2+>. Verapamil inhibited hypertonic K^+, 5-HT and NA induced tension of SHR aortic strip in greater extent than that of KNR aorta. Ca^<2+> influx occured into the aortic smooth muscle cell when aortic specimen was transferred from Ca^<2+>-free Krebs to that containing Ca^<2+>. The rate od influx was larger in KNR aortic specimen than that in SHR. Verapamil inhibited Ca^<2+> influx to the muscle more strongly in SHR than in KNR. These differences in Ca^<2+> dependent contractile responses and Ca^<2+> influx between SHR and KNR suggest that the membranes, especially sarcoplasmic reticulum, of SHR aortic smooth muscle cell have abnormal function as Ca^<2+> mediated regulatory sites controlling its mechanical activity.
- 名古屋市立大学の論文
- 1978-12-28