<Fundamental research Pathogensis>Influence of endothelin-1 on systolic arterial pressure and heart rate in conscious WKY and SHRSP

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In conscious 6-month-old female Wistar Kyoto rats (WKY) and stroke-prone spontaneously hypertensive rats (SHRSP) chronically instrumented for blood pressure (BP) measurement, we investigated the effects of endothelin-1 (ET-1) on systolic arterial pressure (SAP) and heart rate (HR). ET-1 injected intravenously at doses of 0.1,0.3 and 1 nmol/kg evoked a transient dose-dependent fall in SAP with a corresponding increase in HR. The percent changes of SAP and HR were similar in WKY and SHRSP. The initial decrease in SAP was followed by a dose-dependent sustained rise in SAP with a concomitant decrease in HR in WKY as well as in SHRSP. There was no significant difference between the pressor effects in either rat strain, whereas the reduction in HR after administration of a 1 nmol/kg dose was more marked in WKY (p<0.05). Our findings indicated that the initial transient hypotensive and the subsequent long-lasting pressor effect to ET-1 (0.1,0.3 and 1 nmol/kg, bolus i.v.) caused the nonsignificant difference between conscious WKY and SHRSP. The corresponding bradycardic response to the blood pressure elevation was less in SHRSP than in WKY which may be due to an attenuation of the baroreflex sensitivity in the hypertensive rats.
近畿大学の論文
1993-12-30