Effects of nifedipine on coronary reactive and exercise induced hyperaemia.

Abstract

The effects of nifedipine on coronary vasodilation were studied during reactive hyperaemia after a transient coronary occlusion and during active hyperaemia associated with graded treadmill exercise. Studies were performed in 10 chronically instrumented dogs in which left circumflex coronary artery flow was measured with an electromagnetic flowmeter and myocardial oxygen extraction was determined from indwelling aortic and coronary sinus catheters. Thirty minutes after administration of nifedipine (10 micrograms.kg-1 iv), when coronary blood flow, arterial pressure, and heart rate had returned to control values, the vasodilatation following a 10 s coronary occlusion was significantly blunted, so that reactive hyperaemia blood flow debt repayment (mean(SEM)) was reduced from 387(39)% during control conditions to 270(33)% after nifedipine (p less than 0.05). In contrast, nifedipine did not alter the coronary vasodilatation that occurred in response to graded treadmill exercise so that the increase in coronary blood flow during exercise was not different from the control response. Thus, although nifedipine blunted ischaemic coronary vasodilatation during reactive hyperaemia, it did not alter coronary vasodilatation during active hyperaemia resulting from physiological increases of myocardial oxygen consumption.

• Authors: R J Bache, D Quanbeck, D C Homans, X Z Dai
• Journal: Cardiovascular research (Cardiovasc Res) Vol. 21 Issue 10 Pg. 766-71 (Oct 1987) ISSN: 0008-6363 [Print] England
• PMID: 3440269 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Nifedipine

Topics

• Animals
• Arterial Occlusive Diseases (complications)
• Coronary Circulation (drug effects)
• Coronary Disease (complications)
• Dogs
• Hemodynamics (drug effects)
• Hyperemia (etiology, physiopathology)
• Nifedipine (pharmacology)
• Oxygen Consumption (drug effects)
• Physical Exertion
• Vasodilation (drug effects)