Ключ. слова: cytoskeleton, transmitter release, active zone
Індекс рубрикатора НБУВ: Е60*739.11

Рубрики:

Загальна зоологія

Шифр НБУВ: Ж61875 Пошук видання у каталогах НБУВ 

Ключ. слова: synaptic delay, facilitation, "residual calcium", nerve ending, calcium current, temporal course of transmitter release, latency
Індекс рубрикатора НБУВ: Е60*739.1*02

Рубрики:

Загальна зоологія

Шифр НБУВ: Ж61875 Пошук видання у каталогах НБУВ 

In experiments on the frog cutaneous-pectoris muscle, the amplitude-temporal parameters of monoquantum end-plate currents (EPC) and miniature EPC (mEPC) were investigated using extracellular recording. A significant dependence of the risetime of the signals on their amplitude was found after analyzing mEPC; at the same time, such dependence was absent for EPC. Approaches leading to disorganization of the active zones (AZ) of the nerve ending (NE), prolonged action of a Ca-free solution, and denervation resulted in an increased dependence of the risetime of the monoquantum signals on their amplitude; moreover, these dependences became similar for both mEPC and monoquantum EPC. Mathematical simulation showed that the obtained data could be explained by spatial heterogeneity of the sites of spontaneous and evoked transmitter release within the regions of the AZ. A new hypothesis interpreting spontaneous and evoked transmitter release is proposed.

We studied the molecular mechanisms responsible for nitric oxide (NO)-evoked modulation of the synaptic function in the frog neuromuscular junction using inhibitors of adenylate and guanylate cyclases and analogs of cyclic nucleotides. It was shown that application of an exogenous donor of NO, sodium nitroprusside, decreased transmitter release and enlarged the amplitude of voltage-dependent potassium current of the nerve endings. Our results indicate that NO regulates transmitter release and potassium current in the frog neuromuscular junction both via cAMP- and cGMP-dependent mechanisms.