Acute and chronic effects of the converting enzyme inhibitors enalapril and lisinopril on reflex control of heart rate in normotensive man.
The effects of enalapril maleate and its lysine analogue, lisinopril, on reflex control of heart rate after acute and chronic administration were examined in 10 normotensive males. Both drugs reduced blood pressure without change in heart rate after acute dosing and after seven days. Both drugs impaired the vagally mediated early cardiac acceleration associated with lying down (standing to lying test). A similar effect was observed following edrophonium. After lisinopril bradycardia induced by facial immersion (diving reflex) was significantly attenuated. Edrophonium similarly attenuated the bradycardia. Both these reflexes are parasympathetically mediated. Neither drug altered heart rate or blood pressure changes following Valsalva's manoeuvre and the cold pressor test. Plasma noradrenaline was unchanged. Absence of reflex tachycardia with blood pressure reduction by converting enzyme inhibitors may be related to increased parasympathetic activity either centrally or peripherally without impairment of baroreflexes or sympathetic function.
Ajayi
A A
AA
Campbell
B C
BC
Howie
C A
CA
Reid
J L
JL
D000328:Adult; D000806:Angiotensin-Converting Enzyme Inhibitors; D001285:Atropine / Q000494:pharmacology; D001341:Autonomic Nervous System / Q000187:drug effects*; D001794:Blood Pressure / Q000187:drug effects; D004151:Dipeptides / Q000494:pharmacology*; D004491:Edrophonium / Q000494:pharmacology; D004656:Enalapril; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D007101:Immersion / Q000503:physiopathology; D017706:Lisinopril; D008297:Male; D011187:Posture; D012018:Reflex / Q000187:drug effects; D014636:Valsalva Maneuver
D000806:Angiotensin-Converting Enzyme Inhibitors; D004151:Dipeptides; D004656:Enalapril; D004491:Edrophonium; D001285:Atropine; D017706:Lisinopril