Isoflurane does not further impair microvascular vasomotion in a rat model of subarachnoid hemorrhage.
OBJECTIVE
Since isoflurane is known to attenuate endothelium-dependent dilation (EDD) in normal cerebral arterioles, we examined whether the anesthetic has a similar effect and further impairs EDD in vessels exposed to SAH.


METHODS
Autologous blood was introduced in the subarachnoid space and the parietal lobe harvested. Control animals were sacrificed without introduction of blood. The response of microvessles to the endothelium-dependent dilator adenosine diphosphate (ADP) 10(-9)-10(-4) M, the endothelium-independent dilator nitroprusside 10(-9)-10(-4) M, and ET-1 10(-13)-10(-8) M was measured by videomicroscopy in the presence of 0-2 minimum alveolar concentration (MAC) of isoflurane.


RESULTS
Isoflurane attenuated EDD to ADP in control vessels [66 +/- 5% (control) vs 27 +/- 11% (2 MAC) dilation to ADP 10(-4) M, P < 0.05]. Although SAH was associated with reduced dilation to ADP, exposure to isoflurane did not further impair dilation to ADP after SAH [26 +/- 3% (SAH) vs 21 +/- 5% (SAH/2 MAC) dilation to ADP 10(-4) M, P = NS]. Dilation to nitroprusside was not affected by isoflurane or SAH. Constriction to ET-1 was reduced by 2 MAC of isoflurane [21 +/- 1% (control) vs 13 +/- 5% (2 MAC) constriction to ET-1 10(-8) M, P < 0.05], but not by 1 MAC of isoflurane in control vessels. Constriction to ET-1 was greatly attenuated by 1 or 2 MAC of isoflurane after SAH [32 +/- 5% (SAH) vs 18 +/- 4% (SAH/2 MAC) constriction to ET-1 10(-8) M, P < 0.05].


CONCLUSIONS
In rats, isoflurane does not further impair EDD after SAH and modulates the constrictive response to ET-1. Such an effect of isoflurane would not predispose the SAH-exposed vessels to vasospasm.
Park
Kyung W
KW
Department of Anesthesia and Critical Care, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusettes 02215, USA. kpark@caregroup.harvard.edu
Dai
Hai B
HB
Metais
Caroline
C
Comunale
Mark E
ME
Sellke
Frank W
FW
D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid / Q000494:pharmacology; D000244:Adenosine Diphosphate / Q000494:pharmacology; D018685:Anesthetics, Inhalation / Q000633:toxicity*; D000818:Animals; D001160:Arterioles / Q000187:drug effects; D002196:Capillaries / Q000187:drug effects; D002560:Cerebrovascular Circulation / Q000187:drug effects; D019332:Endothelin-1 / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000187:drug effects / Q000502:physiology; D005260:Female; D007530:Isoflurane / Q000633:toxicity*; D008297:Male; D018715:Microscopy, Video; D009599:Nitroprusside / Q000494:pharmacology; D010296:Parietal Lobe / Q000098:blood supply; D051381:Rats; D017208:Rats, Wistar; D013345:Subarachnoid Hemorrhage / Q000503:physiopathology*; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014664:Vasodilation / Q000187:drug effects*; D014665:Vasodilator Agents / Q000494:pharmacology
D018685:Anesthetics, Inhalation; D019332:Endothelin-1; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D009599:Nitroprusside; D000244:Adenosine Diphosphate; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D007530:Isoflurane