Relaxant effects of β-adrenergic agonists on porcine and human detrusor muscle
Article first published online: 16 SEP 2005
Acta Physiologica Scandinavica
Volume 185, Issue 2, pages 151–159, October 2005
How to Cite
Badawi, J. K., Uecelehan, H., Hatzinger, M., Michel, M. S., Haferkamp, A. and Bross, S. (2005), Relaxant effects of β-adrenergic agonists on porcine and human detrusor muscle. Acta Physiologica Scandinavica, 185: 151–159. doi: 10.1111/j.1365-201X.2005.01474.x
- Issue published online: 16 SEP 2005
- Article first published online: 16 SEP 2005
- Received 16 November 2004, accepted 6 May 2005
- detrusor relaxation;
- organ bath;
- smooth muscle
Aim: Relaxant effects of different β-adrenoceptor agonists on porcine and human detrusor were examined. Thus, the β-adrenoceptor subtype mainly responsible for relaxation in the detrusor muscle of pigs was characterized. Additionally, different effects of several β-agonists in both species were shown.
Methods: Experiments were performed on muscle strips of porcine and human detrusor suspended in a tissue bath. The relaxant effects of the non-selective β-agonist isoprenaline, the selective β2-agonists procaterol, salbutamol and the selective β3-agonists BRL 37344, CL 316 243 and CGP 12177 on potassium-induced contraction were investigated. The inhibitory effect of different substances on the maximum contraction and the rank order of potency for endogenous catecholamines was determined in pigs. Furthermore, concentration-relaxation curves were performed for pigs and humans.
Results: Pigs: In the pre-treatment experiments isoprenaline and procaterol showed similar effects. The concentration–response experiments showed that the maximum relaxation induced by procaterol and salbutamol was more than 90%, not significantly different from isoprenaline, whereas the maximum relaxations of CL 316 243, BRL 37344 and CGP 12177 amounted to 68, 70 or 30%, respectively. Rank order of potencies was isoprenaline ≥ adrenaline > noradrenaline. Humans: Isoprenaline, procaterol, salbutamol and CL 316 243 showed a maximum relaxation of 80, 41, 24 and 35% and pD2 values of 6.24, 5.65, 5.48 and 5.55, respectively.
Conclusion: β2-receptors play a main functional role in mediating relaxation of porcine detrusor. Selective β2- and β3-agonists similarly relax the human detrusor. Effects were smaller compared with the pig.