Characterization of the K+-channel-coupled adenosine receptor in guinea pig atria |
| |
Authors: | H. Tawfik-Schlieper K. -N. Klotz V. A. W. Kreye U. Schwabe |
| |
Affiliation: | (1) Pharmakologisches Institut der Universität, Im Neuenheimer Feld 366;(2) II. Physiologisches Institut der Universität, Im Neuenheimer Feld 326, D-6900 Heidelberg, Germany |
| |
Abstract: | Summary In the present work we studied the pharmacological profile of adenosine receptors in guinea pig atria by investigating the effect of different adenosine analogues on86Rb+-efflux from isolated left atria and on binding of the antagonist radioligand 8-cyclopentyl-1,3-[3H]dipropylxanthine ([3H]DPCPX) to atrial membrane preparations. The rate of86Rb+-efflux was increased twofold by the maximally effective concentrations of adenosine receptor agonists. The EC50-values for 2-chloro-N6-cyclopentyladenosine (CCPA), R-N6-phenylisopropyladenosine (R-PIA), 5-N-ethylcarboxamidoadenosine (NECA), and S-N6-phenylisopropyladenosine (S-PIA) were 0.10, 0.14, 0.24 and 12.9 M, respectively. DPCPX shifted the R-PIA concentration-response curve to the right in a concentration-dependent manner with a KB-value of 8.1 nM, indicating competitive antagonism. [3H]DPCPX showed a saturable binding to atrial membranes with a Bmax-value of 227 fmol/mg protein and a KD-value of 1.3 nM. Competition experiments showed a similar potency for the three agonists CCPA, R-PIA and NECA. S-PIA is 200 times less potent than R-PIA. Our results suggest that the K+ channel-coupled adenosine receptor in guinea pig atria is of an A1 subtype.Abbreviations CCPA 2-chloro-N6-cyclopentyladenosine - DPCPX 8-cyclopentyl-1,3-dipropylxanthine - NECA 5-N-ethylcarboxami-doadenosine - PIA N6-phenylisopropyladenosineSend offprint requests to H. Tawfik-Schlieper at the above address |
| |
Keywords: | A1 Adenosine receptors K+-channels Atria Radioligand binding 86Rb+-efflux |
本文献已被 SpringerLink 等数据库收录! |
|