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Vasomotor responses of cerebral arterioles in situ to putative dopamine receptor agonists
Author(s) -
Edvinsson Lars,
McCulloch James,
Sharkey John
Publication year - 1985
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1985.tb08875.x
Subject(s) - apomorphine , dopamine , medicine , endocrinology , agonist , dopamine agonist , dopamine receptor , chemistry , sch 23390 , methysergide , anesthesia , dopaminergic , antagonist , receptor
1 The vasomotor responses of individual cerebral pial arterioles on the convexity of the cerebral cortex to subarachnoid perivascular micro‐injections of dopamine and the putative dopamine receptor agonists, apomorphine, SKF 38393 and LY 141865, have been examined in 38 anaesthetized cats. 2 The perivascular microapplication of dopamine (10 −9– 10 −3 M) effected dose‐dependent reductions in pial arteriolar calibre, with the maximum reductions in calibre (22 ± 2% from preinjection levels: mean ± s.e.) being observed at 10 −3 M. The cerebrovascular constriction produced by dopamine (10 −5 M) could be significantly attenuated by the concomitant perivascular administration of phentolamine (10 −6 M) or methysergide (10 −6 M). 3 The perivascular microapplication of apomorphine (10 −8– 10 −4 M) effected dose‐dependent increases in arteriolar calibre, with the maximum increase (31 ± 6%) being observed with apomorphine (10 −5 M). 4 The perivascular administration of the putative dopamine D 1 ‐receptor agonist, SKF 38393 (10 −9– 10 −4 M) increased arteriolar calibre, with the maximum response (24 ± 3%) being observed with injection of 10 −7 M. The putative dopamine D 2 ‐receptor agonist, LY 141865, also increased cerebral arteriolar calibre, but only at high concentrations (maximum calibre increase 25 ± 6.1 with 10 −4 M). 5 The cerebrovascular dilatations elicited by apomorphine and by SKF 38393 were markedly attenuated by the concomitant perivascular microapplication of the putative dopamine D 1 ‐receptor antagonist, SCH 23390 (10 −8 M). The perivascular administration of SCH 23390 (10 −9– 10 −5 M) per se did not alter arteriolar calibre nor the arteriolar dilatation provoked by microinjections of acidic cerebrospinal fluid. 6 These results point to the presence on cat cerebral arterioles of dopamine receptors (probably of D 1 subtype) mediating dilatation.