Abstract
It is generally accepted that norepinephrine and epinephrine exert their physiological actions by reacting with two distinct types of adrenergic receptors, α- and β-receptors. Dopamine differs from norepinephrine in not having the hydroxyl group in the side chain. It has been found that dopamine in the peripheral tissues evokes a different type of effect, as fall in blood pressure in dog, guinea pig and rabbit (1-5). Specific dopamine receptors in the renal and mesenteric vessels of the dog were proposed (6).
The aim of this paper is to determine if dopamine and its derivatives have specific dopamine receptors in the taenia caecum and tracheal muscle from the guinea pig and the vas deferens from the rat. Furthermore, the role of dopamine in the intestinal smooth muscle will be discussed in this paper.
Some of the results has been briefly reported at the 46 general meeting of the Physiological Society of Japan (7).
