Pharmacological characterization and autoradiographic localization of dopamine receptors in the portal vein

Abstract

1. Dopamine (DA) and DA receptor agonists exert a variety of effects on the cardiovascular system through interaction with specific DA receptors, including decreases in blood pressure and heart rate. 2. The decrease in blood pressure is due primarily to arterial vasodilation. This phenomenon is due to the stimulation of both postjunctional (D1-like or DA1) and prejunctional (D2-like or DA2) receptors causing respectively relaxation of arterial smooth muscle and decrease of the sympathetic vasoconstriction tone. 3. In view of the lack of detailed information on the existence of DA receptors in venous tissue, we have analysed D1-like and D2-like receptors in the rat portal vein using radioligand binding techniques associated with light microscope autoradiography. 4. No D1-like receptors were demonstrated in sections of the rat portal vein, whereas the D2-like receptor ligand, [3H]-spiroperidol, was bound to sections of the vein in a manner consistent with the labelling of D2-like sites. Anatomically, D2-like sites were located within the tunica adventitia, including the adventitia-media border, and in the endothelium. 5. These findings suggest the existence of D2-like but not D1-like receptor sites in the rat portal vein. D2-like sites of the tunica adventitia are probably prejunctional and involved in the modulation of sympathetic outflow. The functional significance of endothelial D2-like sites, if any, should be clarified in future studies.

Dysregulation of dopamine-dependent mechanisms as a determinant of hypertension: studies in dopamine receptor knockout mice

“…The expression of the D 3 receptor in other nephron segments has not been consistent. Nurnberger et al (194) could not detect any D 3 receptor protein in the distal tubule, cortical collecting duct, glomeruli, and renal Vessels. This is in contrast to the report of O'Connell et al (172), in which D 3 receptor protein was found not only in the renal proximal tubule but also in the apical membrane of the distal convoluted tubule and cortical collecting duct (intercalated cells); D 3 receptor protein was also observed in glomeruli and renal blood Vessels.…”

“…In situ hybridization studies have also shown the expression of the D 1 receptor in the rat pulmonary artery as well as the aorta, common carotid, and vertebral arteries. The superior vena cava (119) but not the portal vein expresses D 1 -like receptors (194). In the rat aorta, common carotid artery, and vertebral artery, D 1 receptor mRNA is found only in vascular smooth muscle cells (VSMCs).…”

Localization of peripheral dopamine D1 and D2 receptors in rat corpus cavernosum

“…Using molecular biology techniques peripheral dopamine receptors have been identified outside the CNS, e.g. in the heart, basilar artery, portal vein, cornea of the eye, and in lymphocytes [9,20,21,[32][33][34]. Dopamine receptor subtypes have also been detected in the kidney, ureter and urinary bladder [16][17][18][19]35].…”

Dopamine, Immunity, and Disease

“…It is possible that fluctuations in active and inactive dopamine in the circulation influence the state of various immune cells in the circulation and/or contribute to cardiovascular homeostasis, which may uncover mechanisms and aid in therapeutic discovery for pathogenic states. Within the cardiovascular system, dopamine can act through both D1- and D2-like receptors expressed in the human heart and in renal, coronary, mesenteric, and cerebral arteries in various animal models, although expression levels vary between cell types and species ( Berkowitz, 1983 ; Missale et al, 1988 ; Berkowitz and Ohlstein, 1984 ; Ricci et al, 1994 ; Amenta et al, 1990 ; Gómez de Jesus, 2002 ; Cavallotti et al, 2010 ; Zingales et al, 2021 ). Substantial data across several decades shows that dopaminergic agents affect vasodilation and vasoconstriction in vitro and in humans, dogs, and mice ( Brodde, 1982 ; Lokhandwala and Barrett, 1982 ; Zhao et al, 1990 ).…”