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Attenuation of the Vasoconstrictor Action of Neuropeptide-Y by Calcium-Channel Blockers

First Department of Internal Medicine, Niigata University, Niigata, Japan

Siniti Niwano, M.D.

First Department of Internal Medicine, Niigata University, Niigata, Japan

Masami Aizawa, M.D.

First Department of Internal Medicine, Niigata University, Niigata, Japan

Makoto Tamura, M.D.

First Department of Internal Medicine, Niigata University, Niigata, Japan

Akira Shibata, M.D.

First Department of Internal Medicine, Niigata University, Niigata, Japan

Neuropeptide-Y (NPY) was administered intracoronarily in dogs to see the modification of its vasoconstrictor action by the calcium (Ca)-channel blockers nisoldipine (0.1 µg/kg) and nifedipine (1 µg/kg).

Dogs were anesthetized and the left circumflex artery was cannulated with out opening the chest by using a specially designed cannula perfused at constant pressure. The change in coronary flow due to NPY was determined before and after the systemic administration of the two Ca-channel blockers. With adminis tration of 1 to 2 nmol of NPY, coronary blood flow decreased maximally by 23.4±7.8% without changes in perfusion pressure or central venous pressure and it became significantly less after nisoldipine: 16.0±5.7% (p < 0.02). A simi lar attenuation in the decrease in coronary flow was observed in the nifedipine study: 23.2±7.5% to 12.0±6.7% (p < 0.02). A fall in systemic arterial blood pressure was observed after administration of both Ca-channel blockers, but it was significant only after nisoldipine (p < 0.01). Nonsignificant increases in heart rate were observed after both drugs.

Nisoldipine seemed to attenuate the NPY-induced vasoconstriction in dogs, and its equimolar potency is about ten times that of nifedipine.

Angiology, Vol. 40, No. 10, 890-894 (1989)
DOI: 10.1177/000331978904001006


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