Effects of adrenergic drugs on miniature contractions of isolated dog urinary bladder.
Isolated dog urinary bladder showed spontaneous miniature contractions under a steady state. In dome preparations, norepinephrine and isoproterenol decreased the frequency of miniature contractions, while epinephrine produced biphasic responses on it; increase by low concentration and decrease by high concentrations. The height of miniature contractions was decreased by these drugs. In trigone preparations, norepinephrine and epinephrine increased the frequency of miniature contractions, while isoproterenol decreased it. These drugs decreased the height of miniature contractions. In both preparations, phentolamine enhanced the decreases in frequency and height by norepinephrine, epinephrine and isoproterenol, while propranolol depressed or reversed them. A computer analysis showed positive and significant correlations between changes in tension development of bladder and frequency and height of miniature contractions. Results indicate that miniature contractions in both dome and trigone of isolated dog urinary bladder are increased by activation of alpha-adrenoceptors and decreased by activation of beta-adrenoceptors.
D000818:Animals; D004285:Dogs; D004837:Epinephrine / Q000494:pharmacology; D005260:Female; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects; D009638:Norepinephrine / Q000494:pharmacology; D010646:Phentolamine / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D013566:Sympathomimetics / Q000494:pharmacology*; D001743:Urinary Bladder / Q000187:drug effects*
D013566:Sympathomimetics; D011433:Propranolol; D007545:Isoproterenol; D009638:Norepinephrine; D004837:Epinephrine; D010646:Phentolamine