Responsiveness to D-glucose in neurosecretory cells of crustaceans.

1. An electrophysiological study of the D-glucose sensitivity of X-organ (XO) neurosecretory cell bodies in crayfish was carried out with the use of microelectrodes, perforated, and cell-attached patch-clamp techniques. 2. Glucose depolarizes the membrane potential of XO cells in a concentration-dependent manner. 3. Depolarization produced by glucose initiates a change in the pattern of electrical activity. Silent cells began to discharge action potentials. When bursting cells are depolarized by glucose, their action potentials are no longer grouped in bursts or disappear entirely. 4. Although the membrane potential returns to its initial value after removing glucose from the bath, discharge patterns of the cells may remain different. This suggests that besides the depolarizing effect, once the cells have been exposed to glucose, the sugar switches on a process that is maintained for a long time. 5. Glucose produced a reduction of membrane steady-state conductance, and a shift of reversal potential of membrane currents to a more positive value. 6. Depolarization induced by D-glucose appears to be related with a closure of potassium channels. 7. Glucose effect was thought to be generated by a product of metabolism that would act as intracellular mediator.