Peripheral dopamine receptor subtypes — a closer look

Action of Fenoldopam, a Selective Dopamine (DA₁ Receptor Agonist, on Isolated Human Arteries

“…It is interesting that Berkowitz et al [1985] re ported that the pA2 for SKF 83566, a se lective DAi receptor antagonist chemically similar to SCH 23390, was also substantially higher when determined against dopamine, using phenoxybenzamine-treated rabbit splenic artery segments preconstricted by prostaglandin F, as compared with the pA2 against fenoldopam in arteries preconstricted by noradrenaline and not exposed to phen oxybenzamine. Another possible explanation might be the existence of different subtypes of DA| receptors as suggested by Hilditch and Drew [ 1985b], however the pA2 for SCH 23390 calculated using dopamine as an ago nist in isolated human arteries [Hughes and Sever, 1988] does not differ substantially from the value reported here. Further work is necessary to clarify this issue.…”

“…However, in this context, it should be noted that the affinity of SCH 23390 calculated in this study is lower than that reported by Hilditch and Drew [1985a], who used dopamine as agonist, in the isolated rabbit splenic artery. The reason for this discrepancy is unclear, it may possi bly reflect species differences, as Hilditch and Drew [1985b] have reported that fenol dopam acts as a DA| receptor antagonist in rabbit splenic artery. Alternatively the differ ence in pAi values may be related to the use of phenoxybenzamine by these workers.…”

Receptor for catecholamines responding to catechol which potentiates voltage‐dependent calcium current in single cells from guinea‐pig taenia caeci

“…At DI and D2 dopamine receptors their pA2 is normally in the range 7-8 (Hilditch & Drew, 1985). At higher concentrations than 1 JIM these two antagonists produced strong depression of the voltage-dependent Ca current themselves and 3 JM haloperidol virtually abolished it.…”

Decreased arterial responsiveness to multiple cyclic AMP‐generating receptor agonists in spontaneously hypertensive rats

“…The relaxant responses to dopamine were significantly weaker in the SHR than in the WKY (Figure 3d). These relaxations were diminished by 1 x 10-7M SCH 23390, a selective D,-dopamine receptor antagonist (Iorio et al,.1983; Goldberg et al, 1984;Hilditch & Drew, 1985), suggesting that dopamine produces the relaxation through activation of DI-dopamine receptors.…”

“…Peripheral dopamine receptors are subdivided into D1 and D2 subtypes, primarily on the basis of agonist and antagonist profiles of action (Goldberg et al, 1978;1984;Hilditch & Drew, 1985). The D1-dopamine receptors produce smooth muscle relaxation including vasodilatation in the renal, mesenteric, coronary and cerebral vascular beds, and these relaxations are selectively antagonized by SCH 23390.…”