An analog of bobine PTH [nle-8, nle-18, tyr-34 bPTH-(1-34)
amide, (PTH-Ana)] which is a potent stimulator of renal
adenylate cyclase has been compared with the native
hormone bPTH-(1-84) and the biologically active amino terminal portion, bPTH-(1-34), for its effects on
bone resorption and bone
collagen synthesis in organ culture. All three compounds stimulated the release of previously incorporated 45Ca from cultured fetal rat long bone shafts with similar dose-response curves
at 10(-9) to 3 X 10(-8) M. All three compounds inhibited bone
collagen synthesis as measured by incorporation of
proline into
collagenase digestible
protein, whereas incorporation into noncollagen
protein was not inhibited. The effects were dose related and decreases in percent
collagen synthesis were significant
at 10(-9) M. Thus PTH-Ana appears to have the same effects on
bone resorption and
collagen synthesis as bPTH-(1-84) and (1-34) and is likely to be a valid probe for investigating PTH receptors in bone as well as in kidney.