Effects of atenolol vs diltiazem on the haemodynamic effects of an inhaled beta 2-adrenoceptor agonist.
To determine the effects of concurrent beta 1-adrenoceptor blocker or calcium channel antagonist administration on the haemodynamic sequelae of an inhaled beta 2-selective adrenoceptor agonist bronchodilator, we examined echocardiographically the effects of fenoterol (400 micrograms) by metered dose inhaler following oral pre-treatment with (a) placebo, (b) atenolol or (c) diltiazem. Following placebo, fenoterol produced significant decreases in diastolic blood pressure (14% +/- 6%), total peripheral vascular resistance (TPR) (31% +/- 9%) and end-systolic stress (ESS) (15% +/- 21%). Cardiac output rose significantly (42% +/- 23%) as did heart rate (25% +/- 13%). After atenolol, responses to fenoterol were significantly blunted. Post-fenoterol heart rate, systolic blood pressure, % fractional shortening, stroke volume, ejection fraction, cardiac output and pressure/volume ratio increased significantly less after atenolol pre-treatment as compared to placebo pretreatment. TPR decreased significantly less. After diltiazem pre-treatment, the response to inhaled fenoterol was not different from that following placebo pre-treatment. We conclude that atenolol blunts the haemodynamic changes induced by fenoterol inhalation whereas diltiazem has little effect.
Chapman
K R
KR
Department of Medicine, Toronto Western Hospital, Ontario, Canada.
Galko
B M
BM
Smith
D L
DL
Leenen
F H
FH
D000328:Adult; D001262:Atenolol / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects; D002302:Cardiac Output / Q000187:drug effects; D004110:Diltiazem / Q000494:pharmacology*; D004452:Echocardiography; D005280:Fenoterol / Q000494:pharmacology*; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D006801:Humans; D008297:Male; D014655:Vascular Resistance / Q000187:drug effects
D005280:Fenoterol; D001262:Atenolol; D004110:Diltiazem