Joshi Shailendra, Hartl Roger, Sun Lena S, Libow Adam D, Wang Mei, Pile-Spellman John, Young William L, Connolly E Sander, Hirshman Carol A
Department of Anesthesiology, College of Physicians and Surgeons of Columbia University, New York, New York 10032, USA.
Anesthesiology. 2003 Feb;98(2):412-9. doi: 10.1097/00000542-200302000-00022.
During cerebral angiography, intracarotid infusion of sodium nitroprusside (SNP), an endothelium-independent nitric oxide donor, fails to increase cerebral blood flow (CBF) of human subjects. A confounding effect of intracranial pathology or that of radiocontrast could not be ruled out in these experiments. The authors hypothesized that, if nitric oxide was a significant regulator of CBF of primates, then intracarotid SNP will augment CBF of baboons.
In studies, CBF (intraarterial (133)Xe technique) was measured in healthy baboons during isoflurane anesthesia at (1) baseline and during (2) induced hypertension with intravenous phenylephrine, (3) concurrent infusions of intravenous phenylephrine and intracarotid SNP, and (4) intracarotid verapamil (positive control drug). In studies, the authors measured tissue cyclic guanosine monophosphate (cGMP) by radioimmunoassay after incubating vascular rings obtained from freshly killed baboons (1) with increasing concentrations of SNP and (2) after SNP exposure following preincubation with the radiocontrast agent, iohexhol.
In the studies, coinfusion of intravenous phenylephrine and intracarotid SNP did not increase CBF. However, intracarotid verapamil significantly increased CBF (from 26 +/- 7 to 43 +/- 11 ml x 100 g(-1) x min(-1); P < 0.0001) without a change in mean arterial pressure. In the studies, incubation of intracranial arterial rings in SNP resulted in dose-dependent increases in cGMP concentrations. A similar increase in cGMP content was evident despite iohexhol preincubation.
Collectively, these results suggest that, in healthy baboons, intracarotid SNP does not decrease arteriolar resistance, although SNP could affect proximal arterial tone, as demonstrated by the increase in cGMP content of these vessels.
在脑血管造影期间，向颈内动脉注入硝普钠（SNP，一种不依赖内皮的一氧化氮供体）并不能增加人体受试者的脑血流量（CBF）。在这些实验中，无法排除颅内病变或放射造影剂的混杂效应。作者推测，如果一氧化氮是灵长类动物脑血流量的重要调节因子，那么颈内动脉注入SNP将增加狒狒的脑血流量。
在研究中，使用（133）Xe动脉内技术，于异氟烷麻醉期间在健康狒狒身上测量脑血流量，测量时间点包括：（1）基线期；（2）静脉注射去氧肾上腺素诱发高血压期间；（3）静脉注射去氧肾上腺素与颈内动脉注入SNP同时进行期间；（4）颈内动脉注入维拉帕米（阳性对照药物）期间。在研究中，作者通过放射免疫分析法测量组织环磷酸鸟苷（cGMP），具体操作如下：将从刚处死的狒狒身上获取的血管环（1）与浓度递增的SNP一起孵育，以及（2）在用放射造影剂碘海醇预孵育后再进行SNP暴露后进行测量。
在研究中，静脉注射去氧肾上腺素与颈内动脉注入SNP同时进行时，脑血流量并未增加。然而，颈内动脉注入维拉帕米显著增加了脑血流量（从26±7增加至43±11 ml×100 g-1×min-1；P<0.0001），而平均动脉压未发生变化。在研究中，颅内动脉环与SNP孵育导致cGMP浓度呈剂量依赖性增加。尽管进行了碘海醇预孵育，cGMP含量仍有类似的增加。
总体而言，这些结果表明，在健康狒狒中，颈内动脉注入SNP并不会降低小动脉阻力，但SNP可影响近端动脉张力，这可通过这些血管cGMP含量的增加得到证明。
