Lymphocyte beta 2-adrenoceptors and adenosine 3':5'-cyclic monophosphate during and after normal pregnancy.

1. The beta 2-sympathomimetics, used to inhibit preterm labour, bind predominantly to beta 2-adrenoceptors, activating adenylate cyclase to form adenosine 3':5'-cyclic monophosphate (cyclic AMP), a messenger substance which inhibits the enzyme cascade triggering smooth muscle contraction. beta 2-Adrenoceptor density and cyclic AMP formation can be used as markers of beta 2-adrenergic effect.

Experimental determination of "the law of bone remodeling" and effect of rat parathyroid hormone (1-34) infusion on derived parameters.

The dependence of bone remodeling probability on bone age was investigated by fitting a previously described mathematical model to data describing the decline of radioactivity in the femurs of growing rats prelabeled with [3H]tetracycline. The remodeling probability declined with increasing bone age, but because the data were obtained at the whole bone level, several explanations for this finding are possible, and the results cannot be extrapolated beyond the duration of the experiment. A simpler exponential model that assumes remodeling probability is constant can be used to calculate bone resorption rate within a limited time period.