Influence of beta blockade and intrinsic sympathomimetic activity on hemodynamics, inotropy and respiration at rest and during exercise.
The degree of intrinsic sympathomimetic activity (ISA) is reported to influence the effects of beta blockade at rest, but the effects during exercise are not well documented. Heart rate, blood pressure and left ventricular (LV) function (as assessed by systolic time intervals) were measured at rest and during upright bicycle exercise as well as with flow-volume spirometry at rest in 13 healthy volunteers. The measurements were performed before and 4 and 24 hours after a single oral dose of pindolol (10 mg), nadolol (80 mg) and acebutolol (400 mg) in a double-blind, randomized, crossover manner. All drugs reduced heart rate, but nadolol had the most pronounced and longest bradycardic effect at rest. Diastolic blood pressure was only slightly influenced by the drugs, whereas systolic pressure was significantly lower compared with control values, especially during exercise (p less than 0.001). Neither preejection period (PEP) nor LV ejection time (LVETc) was changed at rest after pindolol, but PEP increased and LVETc decreased significantly after nadolol (p less than 0.05 for PEP and p less than 0.01 for LVETc) and acebutolol (p less than 0.05 for both). During exercise, PEP and LVET were significantly longer after all 3 drugs compared with control values. Only nadolol, which lacks ISA, significantly decreased expiratory flow values (p less than 0.05). Thus, unlike the other beta blockers, pindolol (with strong ISA) did not depress LV function at rest, while during exercise all 3 beta blockers had equal adverse effects. The degree of ISA appears to be important in determining the hemodynamic effects of beta-blocking drugs.
Sundberg
S
S
Gordin
A
A
D000070:Acebutolol / Q000494:pharmacology*; D000293:Adolescent; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000328:Adult; D002986:Clinical Trials as Topic; D004311:Double-Blind Method; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D008297:Male; D009248:Nadolol; D005082:Physical Exertion; D010869:Pindolol / Q000494:pharmacology*; D011412:Propanolamines / Q000494:pharmacology*; D011897:Random Allocation; D012119:Respiration / Q000187:drug effects; D012146:Rest; D013147:Spirometry; D013564:Sympathetic Nervous System / Q000187:drug effects*; D013599:Systole
D000319:Adrenergic beta-Antagonists; D011412:Propanolamines; D009248:Nadolol; D000070:Acebutolol; D010869:Pindolol