Abstract

Introduction

Materials & Methods

Results

Discussion & Conclusion

References

Discussion
Board

Nerve fibers in the adventitial layer of sheep middle cerebral artery were found to contain vasoactive intestinal peptide (VIP) and neuronal type NO synthase (NOS) by immunocytochemistry with specific antibodies. Staining of serial sections demonstrated that VIP and NOS are present in the same nerve fibers. Relaxation of rings of sheep middle cerebral artery, elicited by field stimulation of intramural nerves, was inhibited by incubation with VIP antiserum 1:256, or by the inhibitor of neuronal NOS, L-NAPNA 100uM. Relaxation of sheep middle cerebral artery rings by addition of VIP (20-200 nM) phosphodiesterase inhibitor, zaprinast 10 uM. Addition of VIP 200 nM to rings of sheep middle cerebral artery produced a 2.4 fold increase in cyclic-GMP content measured by radioimmunoassay, and this was prevented by preincubation with L-NOArg 100 uM. It is concluded that VIP-induced vasodialtion in the cerebral artery occurs via activation of NOS and formation of cyclic-GMP. The results suggest that neurally-mediated vasodilation of the sheep middle cerebral artery requires the participation of both VIP and neuronal NOS.

Back to the top.
Presentation Number SAr.m. wadsworth0448
Keywords: vip, nos, neurotransmitters, cerebral arteries, vasodilation