Perfusion measurements. (A) Color photographs of an animal brain recorded at different time points (pre-injection, 10-20 min, 30-35 min, and 60-65 min from ET-1 injection time) by a digital camera of laser Doppler system, corresponding closely with the blood flow image. Look-up table shows arbitrarily assigned perfusion unit (PU) from the lower limit 0 to upper limit 1, 000 and above. The scalps demonstrate the holes and injection sites. (B) Percentage perfusion reduction as a function of time calculated using formula 1. All rats were injected with ET-1 (240 pmol in 3 μL PBS) proximal to the left middle cerebral artery. About 5-10 min after ET-1 injection, pGSN (35.71 pmol in 3 μL saline) was intracranially injected (i.c) at the same site in a group and no injection in the other group. The dotted line represents the average levels in pGSN treated group (N = 3). The solid line represent levels in control group (N = 3). The differences at all-time points were not statically significant.