Dependence of basal cerebral blood flow and cerebral vascular resistance in spontaneously hypertensive rats upon vasoconstrictor prostanoids.
The effects of indomethacin (inhibitor of cyclooxygenase), imidazole (inhibitor of thromboxane A2 synthase) and SQ 29548 (antagonist of TxA2/PGH2 receptors) on basal CBF and CVR were studied in normocapnic and normoxic SHR and WKY rats. CBF was measured by the intracarotid 133Xe technique. CVR was calculated as ratio of mean arterial blood pressure and CBF. Resting CBF did not differ between SHR and WKY. MABP and CVR were significantly higher (p < 0.01) in SHR than in WKY. Indomethacin (6 mg/kg, i.v.) produced a significant long-lasting decrease of CBF and increase of CVR in both strains, although these effects were more pronounced (p < 0.01) in WKY. Imidazole (20 mg/kg, i.v.) had no effect on measured variables in either strain. SQ 29548 (1 mg/kg, i.v.) produced a significant increase of CBF in SHR (p < 0.001) but not in WKY. CVR decreased in SHR parallel to the increase of CBF but remained unchanged in WKY. Our results demonstrate that, in contrast to WKY, basal CBF and CVR in SHR depend upon vasoconstricting prostanoids which act on TxA2/PGH2 receptors but are distinct from thromboxane A2.
Oseka
M
M
Department of Clinical and Applied Physiology, School of Medicine, Warsaw, Poland.
Koźniewska
E
E
D000818:Animals; D001481:Basal Metabolism; D002560:Cerebrovascular Circulation / Q000187:drug effects / Q000502:physiology*; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006973:Hypertension / Q000503:physiopathology*; D007093:Imidazoles / Q000494:pharmacology; D007213:Indomethacin / Q000494:pharmacology; D011453:Prostaglandins / Q000502:physiology*; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D013930:Thromboxane-A Synthase / Q000037:antagonists & inhibitors; D014655:Vascular Resistance / Q000187:drug effects / Q000502:physiology*; D014661:Vasoconstriction / Q000502:physiology*
D016861:Cyclooxygenase Inhibitors; D004791:Enzyme Inhibitors; D007093:Imidazoles; D011453:Prostaglandins; C029899:imidazole; D013930:Thromboxane-A Synthase; D007213:Indomethacin