Treatment with low dose fasudil for acute ischemic stroke in chronic hypertension

Abstract

We investigated the effect of Rho kinase inhibition on changes in cerebral blood flow (CBF), brain injury and vascular function after ischemic stroke in spontaneously hypertensive rats (SHR). Changes in core MCA and collateral perfusion were measured by a validated laser Doppler method. Animals underwent 2 h tMCAO and 2 h reperfusion. Fasudil (0.1 mg/kg, i.v.) or vehicle was given at 30 min ischemia (n = 9/group; mean (SD)). Brain injury was determined by 2,3,5-triphenyltetrazolium chloride staining. To determine the effect of fasudil on vascular function, fasudil was given 10 min before reperfusion and parenchymal arterioles studied isolated (n = 6/group; mean(SD)). Collateral perfusion was low in vehicle-treated SHR (-8(32)%) that changed minimally with fasudil (6(24)%, p > 0.05, effect size: 0.47;95% CI-0.49-1.39). Reperfusion CBF was below baseline in vehicle (-27(26)%) and fasudil (-32(25)%, p > 0.05, effect size: 0.19; 95% CI-0.74-1.11) groups, suggesting incomplete reperfusion in both groups. Fasudil had little effect on brain injury volume (28(13)% vs. 36(7)% in vehicle, p > 0.05, effect size: 0.75; 95% CI-0.24-1.66). In isolated parenchymal arterioles, myogenic tone was similar between groups (37(6)% vs. 38(10)% in vehicle, p > 0.05, effect size: 0.09; 95% CI-1.05-1.21). There were no differences with fasudil treatment vs. vehicle in perfusion, brain injury and vascular function that may be related to the low dose that had minimal blood pressure lowering effect.

Keywords: Acute stroke; animal models; cerebral blood flow; focal ischemia; hypertension.

Figure 1.

Effect of fasudil on changes in collateral perfusion during ischemia. (a) Graph showing changes in collateral perfusion calculated as percent change from prior to treatment (30 min after filament occlusion). Changes in collateral perfusion was minimal and mostly negative in vehicle-treated SHR. Fasudil did not significantly increased collateral perfusion. Graphs showing (b) number, (c) duration, and (d) magnitude of increased collateral perfusion events in vehicle or fasudil-treated SHR. Fasudil treatment did not increase these discrete events.

Figure 2.

Effect of fasudil on changes in ischemic and reperfusion CBF in core MCA territory. Decrease in CBF in response to filament insertion was similar between groups and sustained throughout ischemia. During reperfusion, CBF was lower than baseline in both groups and fasudil had no significant effect. *p < 0.05 vs. baseline using repeated measures ANOVA.

Figure 3.

Effect of fasudil on acute brain injury volume and edema formation. (a) Representative images of rat brain coronal sections showing acute brain injury (white) after TTC staining in each group. Graphs showing (b) brain injury volume and (c) edema formation in vehicle or fasudil-treated SHR. Fasudil treatment had no significant effect on brain injury and edema.

Figure 4.

Effect of fasudil on reactivity of PAs to pressure and vasoactive agents. (a) Graph showing active inner diameters of PAs in response to pressure. Fasudil treatment did not affect inner diameter of PAs at any pressure studied. (b) Graph showing percent tone of PAs at different pressures. Fasudil had no significant effect on percent tone of PAs. Graphs showing (c) percent constriction to U-46619 and (d) percent reactivity to diltiazem. Fasudil had no effect on reactivity to U46619 or diltiazem.