This overview is concerned with the causes of nonresponsiveness to the hypotensive action of beta-adrenergic blocking drugs. The overall hemodynamic response, i.e., a secondary decrease in peripheral vascular resistance, is unrelated to the primary decrease in cardiac output. The reduction in vascular resistance may be triggered by mechanisms residing in the central nervous system, the arterial...

Instillation of pilocarpine-induced a miosis in a rabbit. In an isolated iris sphincter muscle of rabbit, pilocarpine induced a small contraction and behaved as an antagonist of carbachol. The contractile response of an isolated rabbit dilator muscle to a field stimulation was inhibited by pilocarpine. This inhibitory action of pilocarpine was antagonized by atropine in a concentration-dependen...

Neurogenic ATP and nitric oxide (NO) may play important roles in the physiological control of gastrointestinal motility. However, the interplay between purinergic and nitrergic neurons in mediating the inhibitory neurotransmission remains uncertain. This study investigated whether neurogenic NO modulates the purinergic transmission to circular smooth muscles of the hamster proximal colon. Elect...