title: Acute effects of beta 1 agonism with prenalterol on catecholamine circulating levels in patients with congestive heart failure.
abstract: The effects of a single intravenous infusion of prenalterol, a beta 1 selective agonist, on haemodynamics (echocardiography) and venous plasma catecholamine concentration were studied in 8 patients with severe congestive heart failure. In these patients, age-adjusted plasma norepinephrine (NE) and epinephrine (E) levels before prenalterol infusion were higher compared to values found in 10 control healthy subjects (both P less than 0.01). In heart failure patients, circulating NE levels were not dissimilar in 2 samples drawn 60 and 0 minutes before commencing prenalterol infusion (772.0 +/- 131 ng/l [mean +/- SD] and 775.5 +/- 130.0 ng/l respectively). Prenalterol induced a significant improvement in the cardiac index, stroke index, ejection fraction and velocity of circumferential fiber shortening, associated with a moderate but significant decrease in peripheral vascular resistance. All these changes persisted for 60 minutes after the end of infusion. Circulating NE levels were 604.0 +/- 125 ng/l at 60 min. after start of infusion (P less than 0.01 vs pre-infusion levels) and 526.1 +/- 108 ng/l at 60 min. after the end of infusion (P less than 0.01 vs pre-infusion levels). Plasma E showed a slight decrease, which did not attain statistical significance. Heart rate and diastolic blood pressure remained unchanged during and after infusion, while systolic blood pressure increased by 10-15 mmHg during and after infusion. We conclude that a single 1-hour prenalterol infusion in patients with severe congestive heart failure induces an haemodynamic improvement associated with a reduction of previously elevated circulating NE levels. This reduction could indicate a lowering in the intensity of the afferent stimulus for the reflex sympathetic overactivity.
mesh_terms: D000318:Adrenergic beta-Agonists / Q000627:therapeutic use*; D000368:Aged; D002316:Cardiotonic Agents / Q000627:therapeutic use*; D002395:Catecholamines / Q000097:blood*; D004452:Echocardiography; D005260:Female; D006333:Heart Failure / Q000188:drug therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011217:Practolol / Q000031:analogs & derivatives* / Q000627:therapeutic use; D011294:Prenalterol
chemical_list: D000318:Adrenergic beta-Agonists; D002316:Cardiotonic Agents; D002395:Catecholamines; D011294:Prenalterol; D011217:Practolol