Increased efficacy of sodium nitroprusside in middle cerebral arteries following acute subarachnoid hemorrhage: indications for its use after rupture.
Sodium nitroprusside (SNP) is commonly used for controlled systemic hypotension during aneurysm surgery after acute subarachnoid hemorrhage (SAH). Few experimental studies have assessed cerebrovascular responsiveness to SNP acutely after a representative SAH (i.e., following arterial rupture within the subarachnoid space). Instead, most studies have focused on delayed reactivity after slow injections of unpressurized blood throughout several days. In the authors' study, SAH was created by endovascular rupture in spontaneously breathing rats under urethane anesthesia without craniotomy. After 3 hours, proximal middle cerebral arteries (MCAs) were harvested and mounted as ring preparations in vitro. After preconstriction with 30 mM prostaglandin F2a, concentration-response curves were generated to express SNP's sequential relaxation of preconstricted tone. The effective concentration of SNP for 50% relaxation was significantly lower after SAH (p < 0.001) as compared with non-operated and sham-operated controls. There was also a significantly greater maximum percentage relaxation from preconstricted tone (p < 0.001) with SNP. The results of this study suggest that SNP is a potent and efficacious dilator of MCAs in the hours immediately after acute SAH.
Marshman
L A
LA
Department of Neurosurgery, Royal Hallamshire Hospital, Sheffield, United Kingdom.
Morice
A H
AH
Thompson
J S
JS
D000208:Acute Disease; D018686:Anesthetics, Intravenous / Q000008:administration & dosage; D017542:Aneurysm, Ruptured / Q000150:complications* / Q000503:physiopathology; D000818:Animals; D000959:Antihypertensive Agents / Q000627:therapeutic use; D002536:Cerebral Arteries / Q000187:drug effects*; D002560:Cerebrovascular Circulation / Q000187:drug effects; D015237:Dinoprost / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D066298:In Vitro Techniques; D002532:Intracranial Aneurysm / Q000150:complications* / Q000503:physiopathology; D007427:Intracranial Pressure; D008297:Male; D009599:Nitroprusside / Q000008:administration & dosage / Q000627:therapeutic use*; D051381:Rats; D017208:Rats, Wistar; D013345:Subarachnoid Hemorrhage / Q000503:physiopathology*; D014520:Urethane / Q000008:administration & dosage; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014665:Vasodilator Agents / Q000008:administration & dosage / Q000627:therapeutic use*
D018686:Anesthetics, Intravenous; D000959:Antihypertensive Agents; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D009599:Nitroprusside; D014520:Urethane; D015237:Dinoprost