Cyclic AMP-rnediat~ phospho~la~on of calcium channel subunits was studied in vitro and in vivo in preparations from dog heart. Calcium channels in native cardiac membranes were phosphorylated by CAMP-dependent protein kinase (PKA) solubilized with digitonin and subsequently immunoprecipitated using a polyclonal antibody generated against the deduced carboxy-terminal sequence of the cardiac /I subunit. A 62 kDa protein was identified as the major PKA-substrate in the immunoprecipitates. In the intact myocardium, this putative p subunit was found to be phosphorylated in response to CAMP elevating agents. In contrast, no phosphorylation of a protein with an electrophoretic mobility similar to the a, subunit was detected, although 1,4diiydropyridine receptor sites were recovered in the immunoprecipitates. Thus, we suggest that IX&mediated phospho~lation of the b subunit is the major mechanism for @-adrenergic regulation of cardiac L-type calcium channel activity.

Three MAb M2, B6, P1 (IgG1 type) against human urinary trypsin inhibitor (UTI), a glycoprotein with antiinflammatory properties, have been produced by hybridization of mouse myeloma cells P3o1 with spleen cells of immunized mice BALB/c. Competitive ELISA-examination of peroxidase conjugates of M2, B6, and P1 MAb in the presence of the trypsin binding domain shows the highest affinity of M2 antibody for this domain. On the basis of MAb M2 competitive ELISA of UTI concentration in urine is proposed. ELISA detectable changes in the UTI content of urine from patients with nephritis without renal failure can be considered as an early index of renal parenchyma damage.