title: Differential effect of tetrandrine on aortic relaxation and chronotropic activity in rat isolated aorta and atria.
abstract: Tetrandrine is known as a calcium blocker which can induce bradycardia as well as hypotension. It was however reported that the heart rate was unchanged during tetrandrine-induced hypotension. The possibility of different tissue sensitivity to various concentrations of tetrandrine was therefore investigated using the rat isolated aorta and atria. It was found that tetrandrine (1 x 10(-5) M) was sufficient to suppress more than 90% of the aortic contraction induced by norepinephrine (1 x 10(-8) M) or KCl (50 mM). However, only 10% of the initial heart rate was suppressed by 1 x 10(-5) M tetrandrine. It was therefore concluded that the aorta and atria might have different sensitivity to tetrandrine.
authors.forename: K K
authors.initials: KK
authors.lastname: Wong
mesh_terms: D000470:Alkaloids / Q000494:pharmacology*; D000818:Animals; D001011:Aorta / Q000187:drug effects*; D044182:Benzylisoquinolines; D006325:Heart Atria / Q000187:drug effects*; D066298:In Vitro Techniques; D008297:Male; D010946:Plants, Medicinal / Q000737:chemistry; D051381:Rats; D017207:Rats, Sprague-Dawley; D014665:Vasodilator Agents / Q000494:pharmacology*
chemical_list: D000470:Alkaloids; D044182:Benzylisoquinolines; D014665:Vasodilator Agents; C009438:tetrandrine