Cardio-selective beta adrenergic stimulation with prenalterol in the conscious dog.
The effects of cardioselective beta-1 adrenergic agonist, 1-(4-hydroxyphenoxy)-isopropylamino-2-propanol), i.e., prenalterol, were examined on direct and continuous measurements of left ventricular (LV) pressure, diameter, dP/dt, velocity of shortening, arterial pressure, iliac blood flow and heart rate in 10 conscious dogs. Prenalterol was infused on 3 separate days in doses of 1, 2 and 4 micrograms/kg/min for 15 min. The largest dose of the drug increased LV/dP/dt by 70 +/- 7% from 3581 +/- 130, velocity of LV shortening by 27 +/- 4% from 86 +/- 7 mm/sec, heart rate by 51 +/- 9% from 80 +/- 5 beats/min and iliac blood flow by 40 +/- 4% from 134 +/- 15 ml/min and decreased LV end-diastolic diameter by 8 +/- 2% from 35 +/- 2 mm and LV end-systolic diameter by 15 +/- 2% from 24 +/- 2 mm. All these responses were significant, P < .01. Mean arterial pressure did not change. The positive inotropic effects persisted for 1 hr. The lowest dose of the drug studied increased LV dP/dt and velocity but not heart rate. Practolol, a beta-1 adrenergic receptor blocker, prevented the positive inotropic effects and the increases in iliac blood flow indicating that prenalterol exerts its cardiovascular actions primarily by stimulation of beta-1 adrenergic receptors.
D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000818:Animals; D004285:Dogs; D004347:Drug Interactions; D006439:Hemodynamics / Q000187:drug effects*; D009200:Myocardial Contraction / Q000187:drug effects*; D011217:Practolol / Q000031:analogs & derivatives* / Q000494:pharmacology; D011294:Prenalterol; D013268:Stimulation, Chemical
D000318:Adrenergic beta-Agonists; D000319:Adrenergic beta-Antagonists; D011294:Prenalterol; D011217:Practolol