Increased alpha-adrenergic receptors in ischemic cat myocardium. A potential mediator of electrophysiological derangements.

We have recently demonstrated enhanced alpha-adrenergic responsiveness assessed electrophysiologically in ischemic and reperfused myocardium. This study was performed to determine whether ischemia alters alpha 1-adrenergic receptor number (Bmax) of affinity (KD) based on [3H]prazosin binding. Within 30 min after occlusion, Bmax increased in ischemic regions to 207% of control to 27 +/- 2 fmol/mg protein, with the increase persisting (+ 141% of control) during early reperfusion (2 min), before returning to control base-line values (13 +/- 1.6) after 15 min of reperfusion. KD was not altered at any interval studied. Beta receptor number of ([3H]dihydroalprenolol) and Na+-K+ ATPase activity were comparable in control compared to ischemic myocardium although beta-receptor Bmax and KD in both regions decreased during early reperfusion. Thus, the enhanced alpha-adrenergic responsivity previously recognized with ischemia and reperfusion is correlated with an increase in alpha 1-adrenergic receptors.

The analysis of antinuclear and antinucleolar autoantibodies of scleroderma by radioimmunoprecipitation assays.

We have characterized autoantibodies to nuclear and nucleolar antigens in 112 patients with diffuse scleroderma, CREST syndrome (calcinosis, Raynaud's phenomenon, esophageal dysmotility, sclerodactyly, telangiectasias), scleroderma overlap syndromes, or primary Raynaud's phenomenon by indirect immunofluorescence and radiolabeled immunoprecipitation assays. We noted for the first time that anti-Th RNP antibodies represent a common antibody specificity in scleroderma (occurring in 13% of patients with scleroderma-like illnesses) and that anti-NOR 90 antibodies are quite rare in American patients (none found). In addition, we describe 3 new scleroderma-associated autoantibodies.