Daily exercise enhances acetylcholine-induced dilation in mesenteric and hindlimb vasculature of hypertensive rats

The effect of daily spontaneous running (DSR) on endothelial function was e xamined in spontaneously hypertensive rats (SHR). Following 8-11 weeks of D SR (n=15) or sedentary control (SED, n=15), rats were instrumented with art erial and venous catheters and mesenteric and iliac Doppler ultrasonic flow probes. Hemodynamic responses to vasodilator-mediated substances were dete rmined under two experimental conditions; 1) bolus injection of indomethaci n (10 mg/kg) and 4 bolus doses of acetylcholine (0.5-2.0 mu g/kg); 2) bolus injection of N-omega-nitro-(L)-arginine (5 mg/kg) and 4 bolus doses of nit roglycerin (3-12 mu g/kg). Hindlimb vascular conductance decreased more in response to indomethacin in DSR vs. SED rats (-18.3+/-2.8% vs. -10.4+/-2.5% ). However, the mesenteric or hindlimb vascular conductance responses to N- omega-nitro-(L)-arginine were not different between DSR and SED rats. DSR a lso enhanced mesenteric and hindlimb vascular conductance responses to;acet ylcholine. Results suggest that DSR enhances acetylcholine-induced vasodila tion in SHR.