EVIDENCE FOR A PROSTAGLANDIN LINK IN THE PURINERGIC ACTIVATION OF RABBIT BLADDER SMOOTH-MUSCLE

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  • 1 January 1982
    • journal article
    • research article
    • Vol. 220  (2) , 347-352
Abstract
Two independent pathways for contraction coupling are described for the cholinergic and ATP activation of rabbit detrusor smooth muscle. Both ATP (0.1 mM) and carbachol (1.0 .mu.M) promote contraction of the rabbit detrusor muscle that can be selectively blocked, the cholinergic activation with atropine and an ATP-induced sustained contraction with indomethacin (indo). Both agonists promoted uptake of 45Ca, but they mediate this response separately because atropine will not effectively block ATP Ca2+ uptake but will block carbachol Ca2+ uptake. Indo will block the sustained contraction produced by ATP, but will not abolish a rapid phasic twitch-like contraction induced by ATP. Indo will partially block Ca2+ uptake induced by ATP. Radioimmunoassay for prostaglandin(PG)E in bath perfusate showed that ATP markedly increased synthesis of PGE and this effect was sharply reduced by indo and only partially affected by atropine. This suggests a direct link between the purinergic activation, and an increased synthesis of PGE that was indo-sensitive and associated with the sustained ATP-induced contraction. PGE was the probable PG that was released by ATP stimulation rather than PGF2.alpha. because radioimmunoassay for PGF2.alpha. gave low and inconsistent measurements.