Comparative Haemodynamic Studies of Endothelin‐1, ‐2 and ‐3 on Conscious SHRSP and Wky

Depressor and pressor effects of endothelin-1, -2 and -3 in relation to hypertension were investigated in conscious WKY and SHRSP. 2. Changes of systolic arterial pressure to both depressor and pressor responses caused by three doses of endothelin-1, -2 or -3 (0.1, 0.3 and 1 nmol/kg) occurred to a similar extent between WKY and SHRSP. These data showed that endothelins may not exert an important role on the pathogenesis of hypertension. 3. Endothelin-1 decreased the cardiac index more in SHRSP than in WKY, indicating the dominance of ETA receptors in SHRSP compared with WKY. 4. ET-1 was the most potent vasodepressor and vasodilator of three endothelin peptides in rats. 5. During the pressor responses to endothelin-1 and -3, cardiac arrhythmia was observed with high frequency in the animals of both groups, indicating the arrhythmogenic effect of ET.