Ultrastructural Changes in Blood Vessels of Perinephritic Hypertensive Dogs

Abstract

Mesenteric arteries and saphenous veins of control and perinephritic hypertensive dogs were studied with light and electron microscopy. 2 weeks after surgery there are ultrastructural changes, both in arteries and veins which are thought to be of hydroelectrolytic origin. These alterations are more marked 7 weeks after surgery and disappear thereafter. There are signs of increased protein synthesis activity in the smooth muscle of the mesenteric arteries, but not of the saphenous veins obtained 7 and 14 weeks after surgery, leading to a progressive hypertrophy of the muscular cells. The connective tissue augmented proportionally. Degeneration of adrenergic nerves in the arteries, accompanied by a parallel decrease in their noradrenaline content, constituted an unexpected finding clearly deserving further study.

Uptake and Metabolism of Noradrenaline by Blood Vessels of Perinephritic Hypertensive Dogs

“…The deamination pattern was also modified in these strips: the formation of DOPEG was markedly diminished and the formation of DOMA was increased. These results agree well with the degeneration of the sympathetic innervation of the mesenteric arteries of hyperten sive dogs described by Azevedo et al (1981). …”

“…This reduction suggests an impairment of the adrenergic innervation of these vessels; this is confirmed by the ultrastructural studies of Azevedo et al (1981), showing obvious signs of degenera tion of many adrenergic nerve terminals (loss of vesicles, increased density of the matrix, a prominent number of lamellated and nonlamellated dense bodies and even Schwann cells containing debris reminiscent of adren ergic nerves), which became more prominent with increasing duration of hypertension.…”

“…It has been suggested that U-0521 has effects unrelated to the inhibition of COMT (Guldberg and Marsden, 1975), but there is no available explanation for this effect of U-0521. However, these strips presented marked structural changes (Azevedo et al, 1981) and further studies are needed to corre late these changes with the observed effect of U-0521 on accumulation.…”

“…The slight increase in 3H-NA accumula tion in the strips obtained from hypertensive dogs 7-14 weeks after surgery is difficult to explain, although at this time adrenergic de generation was in an early stage (the neuronal uptake of 3H-NA was not yet impaired, since the reduction in amine accumulation due to cocaine was similar in strips obtained from hypertensive dogs, 7-14 weeks after surgery, and in strips from normotensive dogs); fur thermore, the concomitant decrease in me tabolite formation and the increase in arterial wall thickness observed by Azevedo et al (1981) may, at least in part, contribute to the moderate increase in 3H-NA accumulation observed at this stage. 20 weeks after surgery, the degeneration of the sympathetic innervation of the mesen teric arteries was much more advanced, the endogenous NA content being reduced to about one-third of the control NA content.…”

Sympathetic denervation caused by long‐term noradrenaline infusions; prevention by desipramine and superoxide dismutase

“…), as described earlier (Branco et al, 1984). The remaining venous tissue was used for morphological studies, using the methods previously described (Azevedo et al, 1981;Branco et al, 1984;Sarmento et al, 1987) O-methylisoprenaline were separated by column chromatography, as described earlier in detail (Azevedo & Osswald, 1976).…”