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Title: The characterization of cardiac histaminergic chronotropic receptors in the rabbit. Author: Polanin A, Tenner TE, McNeill JH. Journal: Can J Physiol Pharmacol; 1981 Jan; 59(1):14-8. PubMed ID: 6111386. Abstract: The effects of selective histamine receptor analogs were studied in spontaneously beating rabbit atria. Atrial rate was increased by histamine (an H1 and H2 agonist), 4-methylhistamine and impromidine (H2 agonists), and 2-pyridylethylamine (PEA, an H1 agonist). The responses to histamine, 4-methylhistamine, and impromidine were not affected by propranolol (1 x 10(-7) M) or reserpine pretreatment. However, the response to PEA was nearly abolished upon pretreatment with propranolol or reserpine. Cimetidine pretreatment (H2 receptor blockade) competitively antagonised the positive chronotropic effects of histamine, 4-methylhistamine, and impromidine. Promethazine pretreatment (H1 receptor blockade) competitively blocked the chronotropic effects of histamine but had no effect on the responses to 4-methylhistamine or impromidine. These results suggest that stimulation of H1 and H2 receptors will cause a positive chronotropic response.[Abstract] [Full Text] [Related] [New Search]