Separate development of nitric oxide synthase- and vasoactive intestinal polypeptide-immunoreactive nerves arising from the vertebral artery in the rat.

Development of nitric oxide synthase (NOS)-and vasoactive intestinal polypeptide (VIP)-immunoreactive (-IR) nerves supplying the basilar and vertebral arteries (BA and VA) was investigated in White Wistar rats, using double immunohistochemistry. NOS-IR and VIP-IR nerves via the anterior circulation (AC), which mostly expressed NO(+)/VIP(+), extended to the BA during the second postnatal week, and usually reached as far as the rostral two third of the BA on PND 20. NOS-IR nerves were completely lack in the cBA and the VA on PND10, and often absent from these arterial regions even at PND 20. Nevertheless, a small number of VIP(+)/NOS(-) nerves were localized in the walls from the caudal BA (cBA) to the VA on PND 5. On PND 20, they frequently met with the descending NOS-IR and VIP-IR nerves via the AC around the lower portion of the middle BA. Fiber bundles containing NOS(+)/VIP(+) axons were first visualized on the caudal VA at PND 30 and observed frequently at PND 80, with a distinct increase in number of NOS-IR and VIP-IR nerves supplying the cBA and the VA. Thus, NOS-IR nerves coming from the VA develop through its own characteristic sequence that lags markedly behind the time of appearance for VIP-IR nerves from the same vascular route and for NOS-IR and VIP-IR nerves via the AC.

Distribution of choline acetyltransferase in cerebral and extracerebral cranial arteries of the cat. Its relationship to neurogenic atropine-sensitive dilation.

Choline-acetyltransferase (ChAT) activity was surveyed in segments of cranial arteries--both cerebral and extracerebral--from the cat. High levels were found in pial arteries, both cerebral and cerebellar, and in the arteries to salivary glands, tongue, and nose. Intermediate levels were found in the external and internal maxillary arteries and many of their branches. Enzyme levels in the arteries supplying the head--common carotid, vertebral, and in several systemic arteries and veins and also the lingual vein--were probably not significant. Only those vessels that have higher ChAT contents show capacity for neurogenic vasodilation. The dilation of segments of a number of these arteries, the basilar, middle cerebral, lingual, and internal maxillary, is reduced significantly by atropine (5 X 10(-7) M). ChAT activity did not correlate with vessel norepinephrine content. The data may be interpreted as defining a functional vasodilator system to the head encompassing both cerebral and extracerebral arteries that depends in part on a functional cholinergic link involving a muscarinic receptor. It is separate from the adrenergic outflow. The tissues supplied by vasculature receiving this type of innervation are of ectodermal origin.