Noradrenergic hyperinnervation in the caval vein of stroke-prone spontaneously hypertensive rats

1. The distribution of fluorescent noradrenergic (NA) nerve fibres in the caval vein, which originate from the coeliac ganglion, was examined by glyoxylic acid method in stroke-prone spontaneously hypertensive rats (SHRSP) aged 10, 30, 60, 90 and 180 days. The results were compared with those in age-matched normotensive Wistar Kyoto (WKY) rats. 2. The distribution pattern of NA nerve fibres in the caval vein in both strains changed from a meshwork pattern at 10 days of age to a wavelike line arrangement after 30 days of age. 3. The densities of NA fibres of the caval veins in SHRSP were significantly higher (P < 0.01, Student's t-test, 6 d.f.) than those of WKY at all ages examined. The difference in NA fibre density between SHRSP and WKY showed double peaks at 10 and 90 days of age. 4. The present study suggests that hyperinnervation of the caval vein based on the hyperfunction of the coeliac ganglion is an important factor in the development of hypertension and also may participate in increasing cardiac output because the heart of SHR causes marked hypertrophy from 90 days of age.