Receptors for kinins in the human isolated umbilical vein
Department of Pharmacology, Medical School, Université de Sherbrooke, 3001 12th Avenue North, Sherbrooke (Quëbec) J1H 5N4, Canada
- 1The human umbilical vein has been found to contract in response to bradykinin (BK) and desArg9BK.
- 2The rank order of potency of agonists, in the presence of the B1 receptor antagonist Lys[Leu8]desArg9BK, is as follows: [Hyp3, Tyr(Me)8]BK (pD2 8.88) = [Hyp3]BK (pD2 8.86) = LysBK (pD2 8.81) ≥BK (pD2 8.60) > >[Aib7]BK (pD2 6.38) > >desArg9BK and LysdesArg9BK (inactive).
- 3Hoe 140 (pA2 8.42) inhibits the effects of BK while other B2 receptor peptide antagonists are very weak and WIN 64338 is practically inactive.
- 4Venoconstrictor responses to desArg9BK of fresh tissues increase with time during the in vitro incubation and reach a maximum after 4–6 h. The activity of Hoe 140 (pA2 5.48) is negligible against B1 receptor agonists.
- 5When measured in the presence of the selective B2 receptor antagonist Hoe 140 (400 nM), the order of potency of kinin related peptides on the B1 receptor is Lys[desArg9]BK (pD2 8.60)>desArg9BK (pD2 6.69). BK, LysBK, [Hyp3]BK and other B2 receptor agonists are inactive.
- 6The B1 receptor antagonist, Lys[Leu8]desArg9BK (pA2 7.99), inhibits the response of the human vein to B1 receptor agonists (LysdesArg9BK or desArg9BK), but do not alter the effect of BK.
- 7The results summarized in this paper indicate that the human isolated umbilical vein is a sensitive preparation containing both B1 and B2 receptors. The human B2 receptor shows some similarity with that of the rabbit (at least for agonist potencies) and differs from the B2 receptor of the guinea-pig. Compared to the rabbit B1 receptor, the human B1 receptor shows low sensitivity to peptides that lack the N-terminal Lys.