Article: article from journal or magazin.
Calcium movements and the mechanism of the relaxation induced by adenosine in the guinea-pig taenia coli
European Journal of Pharmacology
In Vitro Journal Article Research Support, Non-U.S. Gov't --- Old month value: Apr 13
The effects of adenosine on the calcium contraction of high K+ (low Na+)-depolarized preparations, as well as on the uptake and release of 45Ca, were studied in the guinea-pig taenia coli. Adenosine (10(-4)-10(-3) M) inhibited the calcium contraction of high K+-depolarized preparations, an effect which was mimicked by ATP (10(-4)-10(-3) M), but not by the slowly degradable ATP analog, adenosine 5'-alpha, beta-methylene triphosphate. The high K+ -stimulated calcium influx measured by 3-6 min exposures to 45Ca was not changed by adenosine (10(-3) M). In high K+ solution, adenosine (10(-3) M) increased the fractional rate of efflux of 45Ca-labelled preparations. These results indicate that stimulation of calcium extrusion, but not inhibition of calcium influx, may take part in the mechanism of the relaxation induced by adenosine in the taenia.
Adenosine/*pharmacology Adenosine Triphosphate/analogs & derivatives/pharmacology Animals Biological Transport, Active/drug effects Calcium/*metabolism/pharmacology Colon/drug effects/physiology Female Guinea Pigs Male Muscle Contraction/drug effects Muscle Relaxation/drug effects Muscle, Smooth/*physiology Potassium/pharmacology
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