Original Article Cholinergic Involvement in Vascular and Glucoregulatory Actions of Insulin in Rats

This study was designed to test the glucose metabolic and vasodilator actions of insulin in rats and its relation to cholinergic system–dependent mechanisms. The first group of rats had pulsed Doppler flow probes and intravascular catheters implanted to determine blood pressure, heart rate, and regional blood flows. Insulin sensitivity was assessed by the euglycemic-hyperinsulinemic clamp tech-nique carried out in the absence or presence of atropine. The second group of rats was used to determine the cholinergic contribution to in vivo insulin-mediated glu-cose utilization in individual muscles. Glucose uptake was examined by using [3H]2-deoxy-D-glucose. Muscarinic cho-linergic blockade was found to significantly (P 0.002) reduce insulin sensitivity and to completely abrogate the renal (P 0.008) and hindquarter (P 0.02) vasodilato