[Vasoactive intestinal peptide (VIP) concentration in ischemic rat brain microvessels].
VIP is extensively localized in the brain, spinal cord and peripheral neurons, and is especially rich in the nerves innervating the cerebral vasculature. VIP is a potent vasodilator of cerebral vessels. The aim of this study was to investigate VIP contents in brain microvessels and their changes during incomplete brain ischemia.


METHODS
(1) Bilateral carotid artery ligation was performed in Wistar rats under urethane anesthesia to produce cerebral ischemia, which was further aggravated by bleeding to hypotension with a mean arterial pressure of 50-60 mmHg. At 5, 15 and 30 min after ligation, the rats were decapitated to obtain brain tissue. A sham surgery group served as controls. In some rats cerebral ischemia was confirmed by EEG. (2) Brain microvessels were prepared by brain homogenization in HEPES-Ringer buffer and gradient centrifugation in 30% BSA, followed by filtration through a glass bead column. (3) VIP contents were determined by radioimmunoassay. The results were that VIP contents of 30 min ischemic rats were significantly higher than in the controls (P less than 0.01). VIP contents of cerebral microvessels were also measured in two groups of gerbils. It was found that VIP contents in ischemic gerbils were significantly higher than in the controls (P less than 0.01). These results indicate that: (1) VIP is present in rat and gerbil brain microvessels. (2) During brain injury by ischemia, the increase in VIP content in cerebral microvessels may induce vasodilation and cause an increase in cerebral blood flow. This may well be an autoregulatory response to protect the ischemic brain and may have important pathophysiological implications.
Yang
S
S
PUMC Hospital, Beijing.
D000818:Animals; D001921:Brain / Q000098:blood supply*; D002545:Brain Ischemia / Q000378:metabolism*; D005849:Gerbillinae; D008297:Male; D008833:Microcirculation / Q000737:chemistry; D051381:Rats; D011919:Rats, Inbred Strains; D014660:Vasoactive Intestinal Peptide / Q000032:analysis*
D014660:Vasoactive Intestinal Peptide