Mechanisms of Action of Isoflurane on Contraction of Rabbit Conduit Artery

• Published in: Anesthesia and analgesia Vol. 82; no. 4; pp. 837 - 842
• Main Author: Su, Judy Y.
• Format: Journal Article
• Language: English
• Published: Hagerstown, MD International Anesthesia Research Society 01-04-1996; Lippincott
• Subjects: Anesthetics. Neuromuscular blocking agents; Animals; Aorta - drug effects; Biological and medical sciences; Caffeine - pharmacology; Calcium - metabolism; Endothelium, Vascular - physiology; Femoral Artery - drug effects; Isoflurane - pharmacology; Male; Medical sciences; Muscle Contraction - drug effects; Muscle, Smooth, Vascular - drug effects; Neuropharmacology; Norepinephrine - pharmacology; Pharmacology. Drug treatments; Rabbits; Vasoconstriction - drug effects; Verapamil - pharmacology; Volatile compound; Vertebrata; Femoral artery; Mammalia; General anesthetic; Animal; Blood vessel; Vasoconstriction; Rabbit; Aorta; Smooth muscle; Lagomorpha
• ISSN: 0003-2999; 1526-7598
• DOI: 10.1097/00000539-199604000-00028

Isoflurane may cause differential effects on different vascular beds of the same animal species.The mechanisms of this action have not been elucidated. Accordingly, we compared in rabbit aorta and femoral artery the effects of isoflurane (1-3.3%) in isolated rings (endothelium denuded) activated by norepinephrine, and isoflurane effects on Ca fluxes from the sarcoplasmic reticulum in skinned strips. When <30 nM norepinephrine was used to cause ring contraction, isoflurane increased the force of contraction in aortic rings, but decreased force in femoral arterial rings. At 30 nM norepinephrine stimulation, 3.3% isoflurane decreased the force and, in the presence of verapamil, isoflurane actually increased the force in both arterial types. In skinned strips of both arterial types, isoflurane present during Ca uptake decreased the caffeine-induced tension transients, whereas isoflurane present during Ca release enhanced the transients. Isoflurane potentiated the depression of the tension transients by ryanodine. Isoflurane directly caused contracture even in the absence of caffeine. Thus, isoflurane has similar cellular mechanisms of action in the aortic and femoral arterial smooth muscleinhibiting Ca influx through the sarcolemma, decreasing Ca uptake by the sarcoplasmic reticulum, and enhancing caffeine-induced Ca release from the sarcoplasmic reticulum.(Anesth Analg 1996;82:837-42)