Release of Purines and Noradrenaline by Ouabain and Potassium Chloride From Vascular Adrenergic Nerves

Abstract

Release of [3H]‐noradrenaline and 3H‐purine by ouabain (10−4m) or high KCl (50 mm) was investigated in the superfused rabbit pulmonary arterial segment preincubated with [3H]‐noradrenaline or [3H]‐adenosine. Ouabain elicited a delayed large contraction and a parallel [3H]‐noradrenaline efflux. These were substantially inhibited by Ca2+‐free medium or preincubation with 6‐hydroxydopamine (30 μg/ml, 30 min). Ouabain caused an 3H‐purine efflux which was slower than the [3H]‐noradrenaline efflux. This was inhibited by 6‐hydroxydopamine and in part by phentolamine (3 × 10−6 m), indicating both neuronal and extraneuronal origins of purines. In contrast to ouabain, high KCl appeared to induce predominantly purine efflux, which was phentolamine‐insensitive and 6‐hydroxydopamine‐sensitive, indicative of neuronal origin. It is suggested that the purine efflux evoked by ouabain and high KCl may originate from different neuronal vesicles.

Na/Ca exchange and tension development in vascular smooth muscle: effect of amiloride

“…In our experimental conditions it is unlikely that these routes of Ca influx were operative. In many types of vascular smooth muscle treated with cardiac glycosides or low K solutions the contractions are partially mediated by noradrenaline released from adrenergic nerve endings Katsuragi & Su, 1982;Hayashi & Park, 1984). However, experimental evidence demonstrates that, in guinea-pig aortic strips, the mechanical response to the above stimuli is the result of a purely myogenic mechanism Karaki et al, 1978).…”

Purinergic Signaling in the Airways

“…Evidence for release of NA and ATP as cotransmitters from sympathetic nerves supplying rabbit pulmonary arteries was reported 30 years ago (Katsuragi and Su, 1982). An important advance was made when it was shown that excitatory junctional potentials recorded in the smooth muscle of rat intrapulmonary arteries in response to sympathetic nerve stimulation were mediated by ATP (Inoue and Kannan, 1988).…”

Purinergic Signaling and Blood Vessels in Health and Disease

“…Evidence for release of NA and ATP as cotransmitters from sympathetic nerves supplying rabbit pulmonary arteries was recognized (Katsuragi and Su, 1982;Mohri et al, 1993). An important advance was made when it was shown that EJPs recorded in the smooth muscle of rat intrapulmonary arteries in response to sympathetic nerve stimulation were mediated by ATP (Inoue and Kannan, 1988).…”