Hepatic vasopressin receptors (VPRs) exhibit species heterogeneity—absence of VPRs in sheep liver

Abstract

1. We have studied the binding characteristics of the hepatic VPRs expressed by rat, cow, pig, sheep and human and have demonstrated species heterogeneity.

2. These species differences are manifested as variation in the VPR capacity (rat > cow > pig > human > sheep), and in the affinity of these receptors for their natural ligand AVP (rat = human > pig = cow).

3. A single class of VPRs, with high affinity for AVP, is present in rat, cow, human and pig liver. In contrast, ovine hepatocytes do not express a VPR.

4. The affinity of the V_1a-selective antagonist d(CH₂)₅Tyr(Me)²AVP is highly dependent on the species utilised, such that rat > human > cow.