Involvement of perivascular sensory fibers in the pathophysiology of cerebral vasospasm following subarachnoid hemorrhage.
The involvement of perivascular sensory fibers containing substance P (SP) and calcitonin gene-related peptide (CGRP) in the events occurring in conjunction with subarachnoid hemorrhage (SAH) has been studied in a rat model. Two days after blood injection, the time point at which maximum vasoconstriction is occurring in this model, immunocytochemistry and radioimmunoassay showed a reduction in SP- and CGRP-like immunoreactivity (LI). The quantitative measurements revealed a significant 50% reduction of CGRP-LI and a slight reduction of SP-LI in SAH as compared to controls. This partial reduction in neurotransmitter content (denervation) caused no change in the sensitivity of the rat basilar artery to SP or CGRP as studied using a sensitive in vitro method. However, the maximum relaxant response to CGRP was increased from 52 to 81% (p less than 0.05), while there was no change in the maximum SP-induced relaxations. It is suggested that not only a pre-, but also a postsynaptic modulation of perivascular sensory fibers may occur in experimental SAH.
Department of Experimental Research, Lund University, Malmö General Hospital, Sweden.
L
L
Edvinsson
T
T
Delgado-Zygmunt
R
R
Ekman
I
I
Jansen
N A
NA
Svendgaard
R
R
Uddman
D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism; D002536:Cerebral Arteries / Q000294:innervation* / Q000503:physiopathology; D002546:Ischemic Attack, Transient / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology*; D008297:Male; D009412:Nerve Fibers / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D013345:Subarachnoid Hemorrhage / Q000150:complications*; D013373:Substance P / Q000378:metabolism
D013373:Substance P; D015740:Calcitonin Gene-Related Peptide