The importance of thymus in the pathogenesis of the chronic phase of hypertension in mice following partial infarction of the kidney.

Partial infarction of one kidney and contralateral nephrectomy was followed by a similar initial increase in blood pressure in athymic (nude) and normal mice of the C57/BL/6J strain. The chronic phase of the hypertension was, however, thymus dependent, since the athymic mice failed to maintain an increased blood pressure, in contrast to the normal mice. A response of thymus transplantation in athymic mice was the ability to maintain the blood pressure high in the chronic phase of the hypertension, whereas cyclophosphamide treatment to the normal hypertensive mice decreased the blood pressure in the chronic phase of the hypertension, but not in the early (acute) phase. Some perivascular round cell infiltrations were found in the uninfarcted part of the kidney in normal and thymus-transplanted nude mice after 80 days of hypertension, but the degree of cellular reaction was less than previously observed in the NMRI-strain of mice. Substantial perivascular cellular infiltrations, which appeared to be thymus-dependent, occurred in the ischemic border-zone of the infarcted area. Athymic mice of the NMRI-strain were able to develop the initial blood pressure elevation of DOCA/salt hypertension during the chronic phase of loomis hypertension, in which phase the arterial pressure otherwise would be declining towards normal values.