Effect of mild hypothermia on inodilator-induced vasodilation of pial arterioles in cats.
BACKGROUND
Mild hypothermia has been proposed as a means of providing cerebral protection after traumatic brain injury. However, hypothermia has been shown to alter not only physiologic but also pharmacologic responses. The purpose of this study was to investigate whether mild hypothermia (3-4 degrees C temperature reduction) could alter cerebral vasodilation induced by inodilators, which are characterized by having an inotropic effect in addition to a vasodilatory effect. Isoproterenol (a beta-adrenergic receptor agonist), colforsin dapropate (an adenylate cyclase stimulant), and amrinone (a phosphodiesterase inhibitor) were chosen as inodilators.


METHODS
The cranial window technique, combined with microscopic video recording, was used. Forty-eight cats were randomly assigned to either a normothermic or a hypothermic group (33 degrees C). Isoproterenol, colforsin dapropate, or amrinone was topically applied in the cranial window and the diameter of pial arterioles was measured.


RESULTS
Topical administration of isoproterenol, colforsin dapropate, and amrinone produced a significant dilation in a dose-dependent manner during normothermia. The vasodilation induced by these inodilators was not affected by mild hypothermia.


CONCLUSIONS
The vasodilation induced by topical administration of isoproterenol, colforsin dapropate, and amrinone was not affected by mild hypothermia.
Inoue
Satoki
S
Department of Anesthesiology, Nara Medical University, Kashihara, Japan.
Kawaguchi
Masahiko
M
Kurehara
Koukichi
K
Sakamoto
Takanori
T
Kitaguchi
Katsuyasu
K
Furuya
Hitoshi
H
D000287:Administration, Topical; D000676:Amrinone / Q000494:pharmacology; D000818:Animals; D001160:Arterioles / Q000187:drug effects / Q000502:physiology; D001831:Body Temperature; D002316:Cardiotonic Agents / Q000008:administration & dosage / Q000494:pharmacology*; D002415:Cats; D005576:Colforsin / Q000031:analogs & derivatives* / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D006439:Hemodynamics; D007036:Hypothermia, Induced; D007545:Isoproterenol / Q000494:pharmacology; D010841:Pia Mater / Q000098:blood supply*; D014664:Vasodilation / Q000187:drug effects*; D014665:Vasodilator Agents / Q000008:administration & dosage / Q000494:pharmacology*
D002316:Cardiotonic Agents; D014665:Vasodilator Agents; D005576:Colforsin; D000676:Amrinone; D007545:Isoproterenol