influence of Mg++ and reserpine on the reactivity of rat seminal vesicle to 5-hydroxytryptamine.
The effects of varying the concentration of Mg++ in the incubation medium on the contractile responses of rat isolated seminal vesicle to 5-hydroxytryptamine (5-HT) were investigated in the absence and presence of EDTA. Preparations incubated in Mg++-free and Mg++ excess media showed supersensitivity and subsensitivity to 5-HT respectively. In the presence of EDTA alterations in the sensitivity to 5-HT produced by varying the concentrations of Mg++ were comparatively less. Preparations obtained from reserpinized animals showed subsensitivity in normal and Mg++ excess media and supersensitivity in Mg++-free medium. In the presence of EDTA, reserpinized preparations showed slight supersensitivity in normal Mg++ medium, marked supersensitivity in Mg++-free medium and lesser subsensitivity in Mg++ excess medium. Probably EDTA by more effectively removing Mg++ from the membrane binding sites by chelation makes the membrane permeable to Ca++ leading to supersensitivity to 5-HT (observed only in the presence of EDTA). These results suggest that the failure of reserpine to induce supersensitivity to 5-HT in rat seminal vesicle may be due to an enhanced antagonism of Mg++ on Ca++ movements in this preparation due to the poor capacity of rat tissue to retain Ca++ (Krishnamurty and Grollman, 1976).
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002463:Cell Membrane Permeability / Q000187:drug effects; D004492:Edetic Acid / Q000494:pharmacology; D066298:In Vitro Techniques; D008274:Magnesium / Q000494:pharmacology*; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D051381:Rats; D011919:Rats, Inbred Strains; D012110:Reserpine / Q000494:pharmacology*; D012669:Seminal Vesicles / Q000502:physiology*; D012701:Serotonin / Q000494:pharmacology*
D012701:Serotonin; D012110:Reserpine; D004492:Edetic Acid; D008274:Magnesium; D002118:Calcium