Hypercapnic vasodilatation in isolated rat basilar arteries is exerted via low pH and does not involve nitric oxide synthase stimulation or cyclic GMP production
Research output: Contribution to journal › Journal article › Research › peer-review
The relaxant effect of hypercapnia (15% CO2) was studied in isolated circular segments of rat basilar arteries with intact endothelium. The nitric oxide synthase inhibitor nitro-L-arginine (L-NOARG) and the cytosolic guanylate cyclase inhibitor methylene blue (MB), significantly reduced this relaxation by 54% and 70%, respectively. The effect of L-NOARG was completely reversed by L-arginine. Blockade of nerve excitation with tetrodotoxin (TTX) had no affect on the 15% CO2 elicited vasodilatation. Measurements of cGMP in vessel segments showed no significant increase in cGMP content in response to hypercapnia. L-NOARG and MB, but not TTX, significantly reduced the basal cGMP content in cerebral vessels. Adding 1.5% halothane to the incubation medium did not result in a significant increase in cGMP content. Lowering the pH by cumulative application of 0.12 M HCl resulted in relaxation identical to that obtained by lowering the pH with 15% CO2. In vessel segments in which the endothelium had been removed beforehand 15% CO2 induced relaxation that was not different from that seen in vessels with intact endothelium. L-NOARG had no affect in endothelium denuded vessels. The results suggest that high CO2 elicits vasodilatation of isolated rat basilar arteries by a mechanism independent of nitric oxide synthase (NOS) activity. The markedly reduced basal cGMP levels in cerebral vessels by L-NOARG and MB suggest that there exists a basal NO formation in the cerebral vessel wall.
Original language | English |
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Journal | Acta Physiologica Scandinavica |
Volume | 152 |
Issue number | 4 |
Pages (from-to) | 391-7 |
Number of pages | 7 |
ISSN | 0001-6772 |
DOIs | |
Publication status | Published - Dec 1994 |
- Amino Acid Oxidoreductases/drug effects, Animals, Arginine/analogs & derivatives, Basilar Artery/physiology, Cyclic GMP/antagonists & inhibitors, Hydrogen-Ion Concentration, Hypercapnia/physiopathology, Male, Methylene Blue/pharmacology, Nitric Oxide Synthase, Nitroarginine, Rats, Rats, Wistar, Tetrodotoxin/pharmacology, Vasodilation/physiology
Research areas
ID: 279694034