THE EFFECT OF HEAT-SHOCK ON M-CHOLINOCEPT ORS FROM RAT CEREBRAL-CORTEX MEMBRANES

The major parameters of binding of the specific blocker [H-3]quinuclid inyl benzilate are obtained for M-cholinoceptors of rat cerebral corte x 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 th e 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 t he high-affinity poll (B-1) by 16% (K-dl did not differ front the cont rol); the efficiency of the ligand binding to the receptors (E = B/2K( d)) decreased by 26%, which suggests the decrease in the functional ac tivity 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%; t he efficiency (E-2) increased by 14%.