Does angiotensin-II protect against strokes?

The association between serum glucose to potassium ratio on admission and short-term mortality in ischemic stroke patients

High serum glucose to potassium ratio (GPR) at admission is implicated for a poor outcome in acute brain injury, acute intracranial hemorrhage, and aneurysmal subarachnoid hemorrhage. However, the relationship between GPR and the outcome of ischemic stroke (IS) remains unknown. In all, 784 IS patients from a large emergency Norwegian cohort were included for secondary analysis. The exposure and outcome were GPR at baseline and all-cause mortality within 30 days after the first admission. Multivariable logistic regression analysis was performed to estimate the risk of 30-day mortality based on GPR levels. In addition, we examined whether there was a nonlinear relationship between admission GPR and 30-day mortality using two-piecewise linear regression with a smoothing function and threshold level analysis. The results of multivariable regression analysis showed that GPR at baseline was positively associated with the 30-day mortality (OR 2.01, 95% CI 1.12, 3.61) after adjusting for potential confounders (age, gender, department, serum sodium, serum albumin, serum-magnesium, hypertension, heart failure, chronic renal failure, and pneumonia). When GPR was translated to a categorical variable, the ORs and 95% CIs in the tertiles 2 to 3 versus the tertile 1 were 1.24 (0.60, 2.56) and 2.15 (1.09, 4.24), respectively (P for trend = 0.0188). Moreover, the results of the two-piecewise linear regression and curve fitting revealed a linear relationship between GPR and 30-day mortality. In IS patients, GPR is positively correlated with 30-day mortality, and the relationship between them is linear. The GPR at admission may be a promising predictor for the short-term outcome in IS patients.

Angiotensin converting enzyme inhibition and the upper limit of cerebral blood flow autoregulation: effect of sympathetic stimulation

The effect of stimulation of the cervical sympathetic ganglia on the upper limit of cerebral blood flow (CBF) autoregulation was studied in normotensive Wistar-Kyoto rats (WKY) and in spontaneously hypertensive rats (SHR) following intravenous administration of the angiotensin converting enzyme inhibitor captopril (10 mg/kg). CBF was measured using the intracarotid 133Xe injection method in halothane/nitrous oxide anaesthetized WKY and SHR. Arterial blood pressure was raised stepwise by the intravenous infusion of noradrenaline. Toward the end of the study, Evans blue was injected and the brains examined for gross blood-brain barrier breakdown. In SHR, sympathetic stimulation reextended the upper limit of CBF autoregulation, which was at a mean arterial blood pressure level of 120-139 mm Hg in the control group of eight SHR and above 170 mm Hg in the stimulated group of nine SHR. In the group of nine WKY subjected to sympathetic stimulation, the upper limit of CBF autoregulation was reached at a mean arterial blood pressure level of 110-129 mm Hg as opposed to 90-109 mm Hg in a previous unstimulated group of WKY. In the two groups subjected to sympathetic stimulation, there was no extravasation of Evans blue in any of the brains. In the control group of SHR, in which there had been marked increases in CBF, three out of eight brains had foci with extravasation of the dye. It is concluded that in normotensive and in hypertensive rats sympathetic stimulation attenuates the downward shift of the upper limit of CBF autoregulation, which is known to accompany intravenous administration of captopril.