PMID: 6160333Nov 1, 1980Paper

Presynaptic modulation of heart rate responses to cardiac nerve stimulation in pithed rats

Journal of Cardiovascular Pharmacology
G M Drew

Abstract

The effects of presynaptic alpha-adrenoceptor blockade with phentolamine, before and after inhibition of uptake-1 with cocaine, on the positive chronotropic response to cardiac sympathetic nerve stimulation in pithed rats was investigated. Phentolamine or cocaine each enhanced the cardiac responses to stimulation at 1 Hz for 15 sec by 10-25%; the combination of the drugs caused no greater enhancement than did either drug alone. Cocaine considerably potentiated the tachycardia produced during prolonged stimulation at 0.1 but not at 0.2-1 Hz. Phentolamine potentiated the responses to stimulation at 0.2 and 0.5 Hz by 21 and 12%, respectively, but not those at 0.1 or 1 Hz. After cocaine, phentolamine caused a further small increase in the response at 0.1 Hz but not other frequency. It is concluded that presynaptic alpha-adrenoceptors exert only modest control over the responses of the rat heart to cardiac nerve stimulation and that this modulation is little influenced by uptake-1.

Citations

Jan 1, 1990·Annals of the New York Academy of Sciences·T C Westfall
Jan 1, 1983·British Journal of Clinical Pharmacology·D P NichollsR G Shanks
Jun 1, 1984·British Journal of Pharmacology·S Kalsner, M Quillan
Jun 1, 1984·British Journal of Clinical Pharmacology·D P NichollsR G Shanks

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