The effect of experimental frost-bite on the responses of the rabbit ear-artery to adrenergic and electrical stimulation.
The aim of the present investigation was to study the effect of sub-zero temperatures on the adrenergic activated, smooth muscle-contraction of a peripheral blood-vessel. The central ear-artery of the rabbit was used for this purpose. The artery was stimulated to contract in vitro by activation of phentolamine sensitive, post-junctional, alpha-adrenoceptors by use of noradrenaline, or by noradrenaline released from noradrenergic nerves in the blood-vessel following electrical field stimulation. The effect of freezing the tissue in vivo for 15 min at sub-zero temperatures (-4, -6 and -9 degrees C) was studied in vitro. Exposure to -4 and -6 degrees C did not alter the apparent affinity (ED50) of noradrenaline significantly, when measured immediately, or 2 or 6 days after exposure. The maximal response to noradrenaline was reduced by approximately 54, 74 and 100% following exposure to -4, -6 and -9 degrees C, respectively. The response was completely restored after 2 and 6 days of regeneration in vivo following exposure to -6 degrees C, whereas the response after exposure to -9 degrees C was restored by only about 8 and 30% after 2 and 6 days regeneration, respectively. The maximal response to electrical field stimulation, which was completely inhibited by tetrodotoxin and phentolamine, was reduced by approximately 92% after exposure for 15 min to -4 and -6 degrees C, while it was completely inhibited after exposure to -9 degrees C. The response was restored by only 15-20% following 2 and 6 days in vivo after exposure to -6 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)
Ostnes
J E
JE
Norwegian Defence Research Establishment, Division for Environmental Toxicology, Kjeller.
Aas
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P
D000818:Animals; D001158:Arteries / Q000187:drug effects / Q000294:innervation / Q000503:physiopathology; D002682:Chinchilla; D004431:Ear, External / Q000098:blood supply* / Q000294:innervation; D004558:Electric Stimulation; D005627:Frostbite / Q000503:physiopathology*; D008297:Male; D009416:Nerve Regeneration / Q000502:physiology; D009638:Norepinephrine / Q000494:pharmacology; D010646:Phentolamine / Q000494:pharmacology; D011817:Rabbits; D012039:Regional Blood Flow / Q000187:drug effects / Q000502:physiology; D013566:Sympathomimetics / Q000494:pharmacology*; D013779:Tetrodotoxin / Q000494:pharmacology
D013566:Sympathomimetics; D013779:Tetrodotoxin; D009638:Norepinephrine; D010646:Phentolamine