Effect of nifedipine treatment on cardiac myosin ATPase activity and responsiveness of cardiovascular system in the dog.
Effects of nifedipine treatment on cardiac myosin ATPase activity and responsiveness of cardiovascular system to catecholamine have been studied. Eight mongrel dogs weighing 7.5 to 13.5 kg were given nifedipine orally twice daily (60 mg/day) for 2 weeks. Ten minutes after the first administration of nifedipine (30 mg p.o.) the heart rate increased significantly and it lasted for, at least, 4 hours. Two-week treatment of nifedipine caused a decrease of the resting heart rate, but the maximal heart rate increase by nifedipine administration was almost the same as the one on the first day. The effects of norepinephrine on heart rate and blood pressure, responsiveness of isolated coronary arteries to some agents inducing a contraction and, Ca2+-activated and K+-activated cardiac myosin ATPase activities were not significantly different between control and nifedipine treatment groups.
Higuchi
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Sakanashi
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D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000758:Anesthesia; D000818:Animals; D003331:Coronary Vessels / Q000187:drug effects; D004285:Dogs; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D066298:In Vitro Techniques; D009124:Muscle Proteins / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D009206:Myocardium / Q000201:enzymology*; D009543:Nifedipine / Q000494:pharmacology*; D009638:Norepinephrine / Q000494:pharmacology; D013997:Time Factors
D009124:Muscle Proteins; D000251:Adenosine Triphosphatases; D009543:Nifedipine; D009638:Norepinephrine