Smooth muscle cells are the site of neurokinin-1 receptor localization in the arterial supply of the rat sciatic nerve

The occurrence and distribution of the preferred receptor for the neuropept ide, substance P (SP), the neurokinin-1 receptor (NK1R) was investigated in the vascular supply of the rat sciatic nerve. Messenger RNA for NK1R was d emonstrated by RT-PCR in the epineurial layer where the majority of small a rteries and arterioles feeding the endoneurial vasculature are located. Imm unoreactivity to NK1R-protein was localized on the smooth muscle cells of t hese arterial vessels by means of immunofluorescence using a polyclonal NK1 R antiserum. This muscular localization of NK1R explains the previously rep orted [Zochodne, D.W. and Ho, L.T., J. Physiol., 444 (1991) 615-630] modera te vasoconstrictor rather than vasodilator effects of SP in this vascular b ed. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.