Comparison of beta-adrenoceptors in single smooth muscle cells and in isolated smooth muscle preparations from the guinea-pig taenia caecum.
Single smooth muscle cells were prepared from guinea-pig taenia caecum. To study the beta-adrenoceptors in the single cells, we observed mechanical responses of the single cells to beta-adrenergic drugs and also tested the binding of a [3H]-labelled drug to the single cells. The single cells showed a graded relaxing response to isoprenaline. The concentration-response curve was shifted in a parallel fashion by propranolol, indicating a competitive antagonism. The pA2 value of propranolol was in agreement with that estimated using the intact tissue. The dissociation constant of [3H]-dihydroalprenolol was similar to the value estimated in the microsomal fractions. The apparent dissociation constants of isoprenaline and propranolol estimated from inhibition of the specific binding of [3H]-dihydroalprenolol to the single cells were also in agreement with the values in the microsomal fractions. The results suggest that there is no change in the beta-adrenoceptor mechanism in single smooth muscle cells by isolating the cells.
Koike
K
K
Department of Chemical Pharmacology, Toho University School of Pharmaceutical Sciences, Chiba, Japan.
Takayanagi
I
I
D000818:Animals; D002432:Cecum / Q000166:cytology / Q000187:drug effects; D004082:Dihydroalprenolol / Q000494:pharmacology; D006168:Guinea Pigs; D006632:Histamine / Q000494:pharmacology; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000166:cytology / Q000187:drug effects*; D011433:Propranolol / Q000494:pharmacology; D011943:Receptors, Adrenergic, beta / Q000187:drug effects*; D014343:Trypan Blue / Q000494:pharmacology
D011943:Receptors, Adrenergic, beta; D004082:Dihydroalprenolol; D006632:Histamine; D011433:Propranolol; D014343:Trypan Blue; D007545:Isoproterenol