PubMed Health⌕ Search

Biomedical subjects

B N Veprintsev

Publications and source records attributed to B N Veprintsev.

At least 19 recordsLinked to original sources
PubMed1984

Two-component desensitization of nicotinic receptors induced by acetylcholine agonists in Lymnaea stagnalis neurones.

The kinetics of desensitization induced by different agonists of acetylcholine (ACh) as well as the kinetics of recovery from densensitization, have been studied using the voltage-clamp technique in isolated, identified Lymnaea stagnalis neurones. Desensitization follows the sum of two exponentials: one fast and one slow. The time constant of the fast desensitization component (tau Ids) under ACh application is in the range of seconds at room temperature (18-23 degrees C). It increases upon cooling (Q10 = 2.8 +/- 0.9), decreases with increasing ACh concentration and is independent of membrane voltage. The time constant of the slow component of densensitization (tau Ids) is in the range of tens of seconds. It decreases with increasing drug concentration and is weakly dependent upon temperature (Q10 = 1.3 +/- 0.4). The relative amplitude of the fast component, estimated by back extrapolation to the position of the peak current, increases with agonist concentration and decreases upon cooling. Recovery from desensitization follows the sum of two exponentials with time constants (tau Ir and tau IIr) of the order of seconds and minutes, respectively. Cooling prolongs the slow component (Q10 of tau IIr is approx. 3) and reduces its contribution during recovery. A comparison of the desensitization induced by various agonists indicates that for the small monoquaternary agonists the onset and recovery of desensitization resemble the onset and recovery observed with ACh. For more bulky agonists, like ethoxysebacylcholine, sebacylcholine and suberylcholine, the decay of the response during prolonged application of the agonist may involve an additional blocking process.

Acetylcholine↗
PubMed1980

[Controlled cell cultivation. IV. The cultivation of isolated neurons of the mollusc, Limnaea stagnalis, in a flow-diffusion chamber].

A possibility of the long-term cultivation of isolated neurons of adult molluscs Limnaea stagnalis in a flow-diffusion chamber has been shown. The construction of the chamber is described by the authors elsewhere; the diagram of the pefusion apparatus has been presented. In the process of cultivation, the nerve cells undergo morphological differentiation to form neuron nets on the glass that involve both individual neurons and their aggregates of 2 to 5 cells. By days 16-18 of cultivation, most of the neurons join together to form several large aggregates of 10-40 cells, connected to each other by thick nerve fibre bundles. A sharp decrease of survival time and the complete inhibition of morphological differentiation of neurons was observed when the diffusional exchange between the extracelluar space and the flowing nutrient medium was replaced in the chamber by the medium perfusion through the extracellular (=pericellular) space. The cause of this phenomenon is discussed.

Animals↗
PubMed1976

Completely isolated molluscan neurons. An ultrastructural study.

The neurons of the molluscs Lymnaea and Helix isolated by fermentative digestion followed by mechanical treatment do not differ ultrastructurally from intact ones. These cells have sufficient metabolic reserves and incorporate into RNA 8% of the total radioactive pool, even more than neurons in ganglia under equal conditions. Neuronal damage can occur, mainly during the pipetting, and this is usually expressed in vacuolization of the cytoplasm. It is important to note that alterations in cell ultrastructure develop earlier than changes in the membrane electrical properties. The surface of the isolated neurons is enlarged two-fold due to the infoldings of the cell membrane. So, the specific resistance of soma membrane of these neurons was calculated as 78 +/- 13 komega-sq. cm. On the surface of isolated neurons scraps of glial and neuronal processes not connected with their own cell bodies, and as a consequence not powerful, are sometimes found. Some endings of the neuronal processes on the surface of isolated neurons are ultrastructurally similar to the axo-somatic synapses.

Animals↗