Archive image from page 655 of Currents in biochemical research, 1956;. Currents in biochemical research, 1956; twenty-seven essays charting the present course of biochemical research and considering the intimate relationship of biochemistry to medicine, physiology, and biology currentsinbioche1956gree Year: 1956 ( DAVID NACHMANSOHN AND IRWIN B. WILSON tein, but no information is at present available about the nature of the storage form. During activity, as is well established ex- perimentally, acetylcholine is released from the bound form. The free acetylcholine acts upon a receptor, the ace
Archive image from page 655 of Currents in biochemical research, 1956;. Currents in biochemical research, 1956; twenty-seven essays charting the present course of biochemical research and considering the intimate relationship of biochemistry to medicine, physiology, and biology currentsinbioche1956gree Year: 1956 ( DAVID NACHMANSOHN AND IRWIN B. WILSON tein, but no information is at present available about the nature of the storage form. During activity, as is well established ex- perimentally, acetylcholine is released from the bound form. The free acetylcholine acts upon a receptor, the acetylcholine receptor, and this action is responsible for the change of perme- ELEMENTARY PROCESS ... GLUCOSE 2 ATP >v ANAER 2 PYRUVIC + Oj VIA CITRIC ACID CYCLE 30 ATP OBIC J 2 LACTIC PHOSPHOCREATINE Co A ♦ ACETATE 'V / AT POOL ACETYL - Co A AMP -f PP Fig. 1. Sequence of energy transformations associated with conduction, and integration of the acetylcholine system into the metabolic pathways of the nerve cell. The elementary process of conduction may be tentatively pictured as follows: (7) In resting condition acetylcholine (O-j) is bound, presumably to a storage protein (S). The membrane is polarized. (2) ACh is released by current flow (possibly hydrogen ion movements) or any other excitatory agent. The free ester combines with the receptor (R), presumably a protein. (3) The receptor changes its configuration (dotted line). This process increases the Na ion permeability and permits its rapid influx. This is the trigger action by which the potential primary source of EMF, the ionic con- centration gradient, becomes effective and by which the action current is generated. (4) The ester-receptor complex is in dynamic equilibrium with the free ester and the receptor; the free ester is open to attack by acetylcholinesterase (E). (5) The hydrolysis of the ester permits the receptor to return to its original shape. The permeability decreases, and the membrane is again in its o
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