Nitric oxide modulates angiotensin II-induced endothelial vasoconstrictor prostanoid release.
This study investigated the modulation of angiotensin II-induced endothelial prostanoid release in rabbit aortic rings. Two cumulative dose response curves with 90-min washing interval were performed. Incubation with L-N(G)-nitroarginine methyl ester (L-NAME) 10(-4) M increased angiotensin II maximal contractile response (E(max)). This effect was reversed by indomethacin 10(-5) M, diphenyliodinum 10(-5) M, Tempol 10(-5) M or ascorbic acid 10(-4) M in both cumulative dose response curves and by SQ 29548 10(-6) M in the second cumulative dose response curve. When segments were treated with tetraethylamonium 10(-3) M but not with glibenclamide 10(-5) M during the washing period, L-NAME recovered its ability to enhance the E(max) in arteries incubated with SQ 29548.


CONCLUSIONS
nitric oxide modulates angiotensin II-induced endothelial release of cyclooxygenase-dependent eicosanoids, one of which acts through thromboxane A(2)/prostaglandin H(2) receptors and would decrease K(Ca) channel activity. An increase in free radical production may account for the enhancement of such prostanoid release. Furthermore, it was found that in the present conditions, the release of the hyperpolarizing factor would improve in order to maintain the vascular tone.
Jerez
Susana
S
Departamento de Bioingeniería, Instituto Superior de Investigaciones Biológicas (INSIBIO), CONICET, Facultad de Ciencias Naturales e Instituto Miguel Lillo, Universidad Nacional de Tucumán, Tucumán, Argentina. sjerez@herrera.unt.edu.ar
Peral de Bruno
Maria
M
Coviello
Alfredo
A
D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D001013:Aorta, Thoracic; D001205:Ascorbic Acid / Q000494:pharmacology; D019086:Bridged Bicyclo Compounds, Heterocyclic; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000378:metabolism; D005231:Fatty Acids, Unsaturated; D006834:Hydrazines / Q000494:pharmacology; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology; D008297:Male; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D026902:Potassium Channel Blockers / Q000494:pharmacology; D011453:Prostaglandins / Q000378:metabolism; D011817:Rabbits; D017482:Receptors, Thromboxane / Q000037:antagonists & inhibitors; D019789:Tetraethylammonium / Q000494:pharmacology; D014661:Vasoconstriction; D014666:Vasomotor System / Q000187:drug effects* / Q000502:physiology
D000975:Antioxidants; D019086:Bridged Bicyclo Compounds, Heterocyclic; D016861:Cyclooxygenase Inhibitors; D005231:Fatty Acids, Unsaturated; D006834:Hydrazines; D026902:Potassium Channel Blockers; D011453:Prostaglandins; D017482:Receptors, Thromboxane; D000804:Angiotensin II; D009569:Nitric Oxide; D019789:Tetraethylammonium; C045749:SQ 29548; D019001:Nitric Oxide Synthase; D001205:Ascorbic Acid; D019331:NG-Nitroarginine Methyl Ester; D007213:Indomethacin