[Potassium agonists: regional vasodilator profile in rats].

The systemic and regional (kidney, mesentery, hindlimb) hemodynamic effects of (a) two potassium agonists: cromakalim (1 to 8 micrograms.kg-1.min-1/15 min) and SR 44866 (0.125 to 2 micrograms.kg-1.min-1/15 min) and (b) a calcium antagonist, nicardipine (0.5 to 2 micrograms.kg-1.min-1/15 min) have been investigated by the pulsed doppler technique, and compared in the anesthetized normotensive rat. The two potassium agonists and nicardipine lowered blood pressure (BP) and total peripheral resistance (TPR) dose-dependently and slightly increased heart rate. Cardiac output (QC) remained unchanged. SR 44866 was as potent as nicardipine in reducing BP and about three to four times more potent than cromakalim (the DE20s, doses producing a 20 p. 100 decrease in BP, being: SR 44866: 0.7 micrograms.kg-1.min-1, cromakalim: 2.8 micrograms.kg-1, nicardipine: 0.8 micrograms.kg-1.min-1). At these equihypotensive doses, the three drugs (a) similarly decreased TPR (SR 44866: -16 p. 100, cromakalim: -17 p. 100, nicardipine: -19 p. 100, (b) reduced mesenteric vascular resistance (MVR) (SR 44866: -18 p. 100, cromakalin: -20 p. 100, nicardipine: -21 p. 100) and renal vascular resistance (RVR) (SR 44866: -16 p. 100, cromakalim: -21 p. 100, nicardipine: -13 p. 100 to the same extent as TPR, but (c) SR 44866 and nicardipine reduced hindlimb vascular resistance (HVR) to a larger extent than TPR (SR 44866: -25 p. 100, nicardipine: -25 p. 100.(ABSTRACT TRUNCATED AT 250 WORDS)