Open AccessVariations of Arterial Responses in vitro in Different Sections of Rat Main Superior Mesenteric Artery
Author(s) -
Tolvanen JariPetteri,
Sallinen Kirsimarja,
Wu Xiumin,
Kähönen Mika,
Arvola Pertti,
Pörsti Ilkka
Publication year - 1998
Publication title -
pharmacology & toxicology
Language(s) - English
Resource type - Journals
eISSN - 1600-0773
pISSN - 0901-9928
DOI - 10.1111/j.1600-0773.1998.tb01447.x
Subject(s) - apamin , vasodilation , acetylcholine , mesenteric arteries , nitric oxide , sodium nitroprusside , artery , superior mesenteric artery , medicine , endocrinology , chemistry , hyperpolarization (physics) , nitric oxide synthase , potassium channel , anesthesia , anatomy , organic chemistry , nuclear magnetic resonance spectroscopy
We examined the control of vascular tone in rat main superior mesenteric artery. Three standard rings (3 mm in length) of the mesenteric artery were cut, beginning 5 mm, 13 mm and 21 mm distally from the mesenteric arteryaorta junction. In noradrenaline‐precontracted rings, relaxations to acetylcholine in the absence and presence of the cyclooxygenase inhibitor diclofenac, did not differ in the studied sections. However, the nitric oxide synthase inhibitor, N G ‐nitro‐L‐arginine methyl ester, attenuated the diclofenac‐resistant responses to acetylcholine more effectively in the proximal than the distal section. Glibenclamide, an inhibitor of ATP‐sensitive K + channels, diminished relaxations evoked by acetylcholine only in the distal section, whereas the inhibitor of Ca 2+ activated K + channels, apamin, attenuated the responses in all sections. Furthermore, relaxation sensitivity to nitroprusside and isoprenaline was lower in the proximal than distal section. Arterial contractile sensitivity to noradrenaline and potassium chloride was higher, while the maximal contractile force generation was lower in the proximal than the distal part. In conclusion, in different sections of rat main superior mesenteric artery considerable variability was observed in vasoconstrictor and vasodilator responses, as well as in the contribution of endothelial nitric oxide and endothelium‐mediated hyperpolarization to vasodilation. Therefore, the present results emphasize the fact that only corresponding vessel segments should be used when investigating the control of arterial tone.