TY - JOUR T1 - CARDIOVASCULAR AND BRONCHOMOTOR RESPONSES TO SELECTIVE <em>BETA</em> ADRENERGIC RECEPTOR AGONISTS IN THE ANESTHETIZED DOG JF - Journal of Pharmacology and Experimental Therapeutics JO - J Pharmacol Exp Ther SP - 445 LP - 455 VL - 189 IS - 2 AU - Martin A. Wasserman AU - Bernard Levy Y1 - 1974/05/01 UR - http://jpet.aspetjournals.org/content/189/2/445.abstract N2 - This investigation compared the selectivity of the beta adrenergic receptor agonists, salbutamol and terbutaline, with the relative nonselectivity of isoproterenol on cardiac, vascular and bronchiolar responses in anesthetized dogs. Dose-response data were obtained and the geometric mean ED values and relative potency ratios were calculated. From these data, the relative order of agonist potency appears to be: isoproterenol &gt; salbutamol &gt; terbutaline. Whereas isoproterenol was a potent activator of all beta receptors, salbutamol and terbutaline were relatively more potent activators of pulmonary and vascular beta receptors than of cardiac beta receptors. For reducing histamine-induced bronchospasm salbutamol was ½ as potent and terbutaline was ⅙ as potent as isoprotenenol. For vascular responses salbutamol was 1/20 and terbutaline was 1/30 to 1/20 as active as isoproterenol. For cardiac rate and force, both salbutamol and terbutaline produced dose-response curves that were less steep than those for isoproterenol and that did not approach the same maximum level produced by isoproterenol. A comparison of the interactions of the three agents on the receptors studied suggests the existence of three different beta adrenergic receptor subtypes in the dog: one in cardiac, another in vascular and a third in bronchiolar muscle. © 1974 by The Williams &amp; Wilkins Co. ER -