Evidence that ATP and noradrenaline are released during electrical field stimulation of the rat isolated seminal vesicle.
The effects of electrical field stimulation (at 1-100 Hz with 20-25 V, supramaximal, and 0.2 ms pulse duration, for 10-20 s), on tone and contractility of rat isolated seminal vesicle was studied, in the absence and presence of specific antagonists (phentolamine, 1 microM, alpha, beta-Me-ATP, 10 microM, and verapamil, 1 microM). The aim was to provide pharmacological evidence of the release of ATP, alongside NA, during electrical stimulation of the rat seminal vesicle. Electrical field stimulation of the rat seminal vesicle produced frequency-dependent contractions. At low rates of stimulation (1-20 Hz), only small tonic contractions were observed (0.3 g tension), whereas at high rates of stimulation (80-100 Hz), only phasic contractions (2-3 g) were seen. However, at intermediate rates of stimulation (e.g. 50 Hz), a biphasic response was produced: an initial fast, twitch-like response (phasic), followed by a slow tonic contraction. The phasic contraction was blocked by the stable analogue of ATP (alpha, beta-Me-ATP), which desensitizes P2-purinoceptors. The tonic contraction is adrenergic and was blocked by phentolamine. Verapamil reduced both types of contractions in this preparation and the block was unselective on tonic versus phasic contraction. It was concluded that electrical field stimulation produced frequency-dependent contractions tonic and phasic in the rat seminal vesicle. These responses were blocked by specific antagonists, suggesting the presence of different types of neurotransmitters released during electrical stimulation of the rat seminal vesicle.
Respiratory and Anaesthetics Unit, Hospital for Sick Children, London, England.
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Wali
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Greenidge
D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D004558:Electric Stimulation; D066298:In Vitro Techniques; D008297:Male; D009638:Norepinephrine / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012669:Seminal Vesicles / Q000187:drug effects / Q000378:metabolism*
D000255:Adenosine Triphosphate; D009638:Norepinephrine