CONTRACTILE RESPONSES OF THE HUMAN URINARY-BLADDER, RENAL PELVIS AND RENAL-ARTERY TO ENDOTHELINS AND SARAFOTOXIN-S6B

1. 1. Endothelin-1 (ET-1), endothelin-3 (ET-3) and sarafotoxin S6b (SRFTX) produced a concentration-dependent tonic contraction of the human isolated urinary bladder, renal pelvis and renal artery with threshold at nM concentration. 2. 2. In the bladder, the following order of potency was found: ET-1 > SRFTX > ET-3. In the renal pelvis, all peptides displayed similar affinity but, at high concentrations the maximal response was highest for SRFTX followed by ET-1 and ET-3. In the renal artery ET-1 and SRFTX were about equipotent and equieffective while ET-3 produced only a slight and inconsistent (2 out of 5 cases) vasoconstrictor response. 3. 3. As shown previously for the human bladder muscle, the response to ET-1 in the renal pelvis was nifedipine (1 μM)-resistant while a consistent fraction of the response was blocked by nifedipine in the human renal artery. 4. 4. These findings indicate that peptides of the endothelin family exert a potent contractile effect on various human smooth muscles. Participation of dihydropyridine-and voltage-sensitive calcium channels in the contractile response produced by these peptides may vary from one organ to another. © 1990.