Effect of rubidium on responses of rabbit vas deferens to transmural stimulation and to noradrenaline.
The effects of 2 mM RbCl on adrenergic transmission in rabbit vas deferens were investigated. Rubidium, but not potassium, markedly potentiated the sustained, secondary contractile response to transmural stimulation at 2--16 Hz. This effect was not abolished by indomethacin. Significant spontaneous desensitization to (--)-noradrenaline occurred, but this was prevented by the addition of 2 mM RbCl or KCl. Addition of 2 mM RbCl, but not of 2 mM KCl, significantly increased the amount of [3H] (+/-)-metaraminol released on transmural stimulation at 5 Hz, without affecting the uptake of [3H] (+/-)-metaraminol over a 30 min period. It is suggested that rubidium mainly potentiated responses of rabbit vas deferens to transmural stimulation by increasing transmitter release, possibly as a result of prolongation of the action potential.
D000818:Animals; D004558:Electric Stimulation; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology; D008297:Male; D008680:Metaraminol / Q000378:metabolism; D009119:Muscle Contraction / Q000187:drug effects; D009638:Norepinephrine / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D011817:Rabbits; D012413:Rubidium / Q000494:pharmacology*; D013268:Stimulation, Chemical; D014649:Vas Deferens / Q000187:drug effects / Q000502:physiology*
D008680:Metaraminol; D012413:Rubidium; D009638:Norepinephrine; D007213:Indomethacin