Effect of somatotropin(STH), parathyroid hormone (PTH) and calcitonin (CT) on cAMP-content of growth cartilage in uremia

Abstract

Retardation of growth is a well known feature in uremic children. There is considerable evidence that several hormone systems,which play an important role in normal growth,e.g. STH,PTH are altered in uremia. Adenylate cyclase mediates the action of most of these hormones on cell proliferation in the chondrocytes. The effects of STH,PTH and CT on cAMP content of cartilage was investigated. Methods:Male Wistar rats(60gBW)were bilaterally nephretomized(NX)or sham-operated(SO)24h before sacrifice. Bovine STH(6h),PTH and CT(15min) was given i.v. cAMP in cartilage was measured by RIA. Results: Basal cAMP content in cartilage was not different between NX and SO. Stimulation with 40IU i.v. PTH caused a significantly(p 0.01)lower cAMP increment in NX(11.4±1.0;SEM; n=20)than in SO(24.0±2.6).CT(2.5U)administration resulted in higher cAMP in NX(23.8±1.8;n=19)vs. SO(16.6±1.6). STH(0.1-5.14)was without effect on cAMP in NX or SO,but enhanced 3Thymidine incorporation. Discussion: Target organ resistance to PTH seems to be reflected by diminished cAMP response in uremic growth cartilage. CT has the opposite effect on NX.In the above model,with the dose of STH used,no effect on cAMP could be seen. Our present results provide evidence that in acute uremia the cAMP system may be involved in the growth abnormality of RF.