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Biomedical subjects

G N Akoev

Publications and source records attributed to G N Akoev.

At least 91 records · Page 5Linked to original sources
PubMed1981

[Mechanisms of synaptic transmission in the ampullae of Lorenzini in skates].

Effects of Mg2+, L-glutamate (L-GLU) and L-glutamic acid diethyl ester (GDEE) on background and evoked activity of the ampullae of Lorenzini were studied in marine skates (Raja clavata). Perfusion of the basal membrane with 10(-4)-10(-5) M L-GLU produced significant and reversible changes in background firing rate depending on its initial level. When excitability was blocked by perfusion with Mg2+, the background activity could be restored in L-GLU (10(-4)-10(-5) M) Mg2+-containing solution. GDEE (10(-3)-10(-4) M) blocked the synaptic transmission. The results are consistent with the view that L-GLU is the synaptic transmitter in the ampullae of Lorenzini of the skate.

Animals↗
PubMed1980

L-glutamate as possible neurotransmitter in the ampullae of Lorenzini of the skate.

Effects of Mg2+, L-glutamate (L-Glu) and L-glutamic acid diethylester (GDEE) on resting and evoked activities of the ampullae of Lorenzini were studied in marine skates (Raja clavata). Perfusion of the basal membrane with 10(-4)-10(-5) M L-Glu produced significant and reversible changes in resting firing rate depending on initial resting rate. When synaptic transmission was blocked by perfusion with elevated Mg2+, the resting activity was restored if L-Glu (10(-4)-10(-5) M) was added. GDEE (10(-3)-10(-4) M) blocked the synaptic transmission. The results are consistent with the view that L-Glu is the synaptic transmitter in the ampullae of Lorenzini of the skate.

Animals↗
PubMed1980

[Effect of calcium ions on the electrical and temperature sensitivity of the ampullae of Lorenzini of Black Sea skates].

Changes in the ambient calcium concentration affected similarly both thermal and electrical sensitivity of electroreceptors of the Lorenzini ampullae in the skates. In Ca-free solution containing EGTA the sensitivity first decreased, then increased and after that blocking of synaptic transmission occurred. In Ca-rich solution both thermal and electrical sensitivity decreased. Changes of spontaneous activity occurred much later than those of evoked responses.

Animals↗
PubMed1979

[Analysis of the mechanism of amplitude change in Pacinian corpuscle receptor potential in a solution with a decreased calcium ion concentration].

The effect of Ca2+-free solution on the amplitude increase in the receptor potential (RP) of Pacinian corpuscles was studied using external perfusion technique. The RP amplitude increased in Ca2+-free solution. It was blocked after addition of 10-20 mM of tetraethylamonium. A temporary increase in the RP amplitude is seen in the solution with 0.2 mM of 2.4-dinitrophenol. Sensitivity of the receptor membrane to mechanical stimuli does not change in Ca2+-free solution. It is suggested that near the mechanosensitive ionic canal of Pacinian corpuscle receptor membrane the fixed negative charges which could influence the "gate" system state of the mechanosensitive canal are absent.

Animals↗
PubMed1978

[Analysis of the mechanism of perception of temperature stimuli by the ampullae of Lorenzini of Black Sea skates].

The single nerve fibre responses of the Lorenzini ampulla to thermal stimulation were studied in the Black Sea skates, Trygon pastinaca, and Raja clavata. Cooling of sea water applied to the ampulla capsule or to the skin overlying the sensory organ increased firing rate wheras warming led to transient decrease in frequency. The thermal sensitivity or receptors was found to depend on threshold to electric current. Static discharge rate of the receptors has positive or negative temperature coefficient according to the temperature range. Cooling of sea water increased the latency of response to electric stimuli. Biological significance of the thermal sensitivity of the Lorenzini ampulla is discussed.

Adaptation, Physiological↗
PubMed1977

[Effect of acetylcholine and cholinolytics on the activity of Pacinian corpuscles].

The effect of acetylcholine and cholinergic antagonists (atropine, d-tubocurarine, hexamethonium) was studied as applied to isolated decapsulated preparations. Acetylcholine (10(-5)-10(-4) g/ml) enhanced the sensitivity of the receptors to mechanical stimuli due to increased excitability of the Ranvier node. The amplitude of the receptor potential decreased. Cholinergic drugs did not block the responses of receptors to mechanical stimuli. The results provide evidence against the role of acetylcholine as a transmitter in the Pacinian corpuscles.

Acetylcholine↗
PubMed1977

[Effect of magnesium and calcium ions on the electrical activity of Pacinian corpuscles].

The effect of magnesium and calcium ions of the electrical activity of Pacinian corpuscles was studied in isolated decapsulated preparations. The sensitivity of the corpuscles and the amplitude of receptor potential increased in magnesium-rich solution (5-15 mM). The amplitude of receptor potential increased over the first 60 min and then decreased in calcium-free EDTA solution. Magnesium ions slow down or prevent the depressant effects of the lack of calcium on the receptor potential. Divalent cations are supposed to take no part in mechano-electrical transduction conduction in Pacinian corpuscles.

Animals↗
PubMed1976

K and Na ion content in the Pacinian corpuscle fluid and its role in the activity of receptors.

1. Potassium and sodium concentrations within the Pacinian corpuscle fluid have been investigated in adult cats. The sodium and potassium contents of samples were estimated by means of integrative ultramicroflame photometry. 2. The analytical results showed the values of the potassium concentration in the Pacinian corpuscle fluid and in the blood plasma to be 6.19 +/- 0.72 and 2.78 +/- 0.38 mequiv/1, respectively. 3. The increasing excitability of the Pacinian corpuscle in potassium-rich solution was shown by electrophysiologic methods. In potassium-free solution two phases of changing receptor excitability were observed. 4. Removal of sodium from external solution reduced the receptor potential to 10% of its original value. 5. Some mechanisms of the increase in excitability of primary tissue mechanoreceptors and secondary mechanoreceptors of the sense organs are discussed.

Animals↗
PubMed1975

[Functional features of the electroreceptors of several electric and non-electric fish].

The effect of the electric, magnetic, and mechanical stimulation of the electroreceptors was studied in marine skates (Trigon pastinaca, Raja clavata, and Torpedo marmorata) by recording single nerve fiber responses. The following two types of backbround dischanges were found with regular activity and bursting. In some fibres the bursts of impulses appeared simultaneously with respiration while in the others the activity was suppressed. The current threshold of the clear-cut responses were equal to 10- minus 9--10- minus 11 A/mm-2. The activity of the electroredeptors was modified by introducing a conductive or nonconductive object into the water. High sensistivity of the electroreceptors to weak magnetic field was shown. The biological role of the electroreceptors is discussed.

Animals↗