Increased responses to intravenous injections of the full alpha 2-adrenoceptor agonists, alpha-methyl noradrenaline and noradrenaline, were observed in conscious rabbits with perinephritis hypertension. However, responses to the partial agonist, BHT 920, and the antagonist, idazoxan, were unchanged.
Vasodilator substances act either directly on vascular smooth muscle (e.g., adenosine) or indirectly (e.g., acetylcholine) on endothelial cells that respond by releasing an unknown powerful, short-lived relaxing factor. To determine whether chronic hypertension or hypercholesterolemia or both would