The effect of heat shock on M-cholinoceptors from rat cerebral cortex membranes

The major parameters of binding of the specific blocker [H-3]quinuclidinyl benzilate are obtained for M-cholinoceptors of rat cerebral cortex membranes. It was shown that one receptor binds two molecules of the ligand; two discrete receptor pools were revealed, which differed in the sensitivity (K-dl = 0,35 +/- 0,03; K-d2 = 1,79 +/- 0,21 nM) and the number of the ligand binding sites (B-1 = 468 +/- 54; B-2 = 864 +/- 81 fmol/mg protein). Heat shock decreased the number of receptors of the high-affinity poll (B-1) by 16% (K-dl did not differ front the control); the efficiency of the ligand binding to the receptors (E = B/2K(d)) decreased by 26%, which suggests the decrease in the functional activity of the receptors of this pool. In the low-affinity pool (B-2), the number of receptors increased by 39%, and K-d2 decreased by 22%; the efficiency (E-2) increased by 14%.