Transient and persistent changes in rabbit blood vessels associated with maintained elevation in arterial pressure.

ABSTRACT

Arteries and veins of hypertensive rabbits were examined 8 weeks after partially constricting the abdominal aorta above both kidneys, and compared with those from sham-operated animals. Structural and functional changes in blood vessels after 2 weeks, when the arterial pressure first attained a new elevated level, have been described previously, and are now compared with changes 6 weeks later. The increase in blood vessel mass could be correlated with an increase in deoxyribonucleic acid (DNA) content. In contrast to the status at 2 weeks postoperatively, there was no increased uptake of 3H-thymidine, 3H-proline, or 3H-lysine at 2 months. Furthermore, at this time cell nuclei labeled with 3H-thymidine were infrequent. Some vessels showed evidence of change in the physical characteristics of their wall. Only minimal changes were observed in those parameters of adrenergic nerve function measured -- neuronal 3H-norepinephrine uptake and vessel wall catecholamine content -- that had been markedly changed at 2 weeks. The results of this work, together with those of other studies of this model, suggest two phases of response of the arterial wall to pressure rise an initial dynamic proliferative cellular response mainly of vascular smooth muscle associated with changes in adrenergic neuronal parameters, and a subsequent equilibrium phase characterized by an increased number of smooth muscle cells, some changes in the extracellular components, and minimal changes in the adrenergic innervation.