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Biomedical subjects

V Kecskeméti

Publications and source records attributed to V Kecskeméti.

3 recordsLinked to original sources
PubMed1978

Comparative effects of prostaglandin F2alpha and A2 on the cardiac transmembrane potentials.

PGF2alpha and PGA1 similarly to PGE1 and PGE2 exerted a dose-dependent dual effect on the maximum rate of depolarization (Vmax) of the cat and guinea-pig left auricle. Low concentrations (0.5 and 1.0 microgram/ml) of PGF2alpha caused a marked increase of Vmax which was proportional to the dose in both species, while the overshoot (OS) remained unchanged. PGF2alpha in a dose of 5 micrometer/ml significantly decreases OS but did not alter Vmax, in a dose of 10 microgram/ml, however, evoked a considerable decrease of Vmax, too. These changes were not related to those in the resting potential (RP). With respect to the repolarization phase no biphasic effect was observed. PGA1 in a dose of 0.02 microgram/ml significantly increased Vmax and RP, too. In the presence of 0.1 microgram/ml of PGA1 Vmax remained unchanged, only a significant hyperpolarizing effect could be observed. A higher concentration (1.0 microgram/ml) of PGA1 evoked a significant decrease of Vmax, without changing RP. The examined concentrations of PGA1 accelerated the initial repolarization (20 and 50% repolarization phase).

Animals↗
PubMed1978

Effect of verapamil and D 600 on cardiac transmembrane potentials.

The effects of verapamil and D 600 on the transmembrane potential of guinea pig and cat left auricles were analysed using KC1 filled intracellular microelectrodes. Verapamil (2 microgram/ml) seemed to have no considerable effect on resting potential (RP) and on the maximum depolarization rate (Vmax) of the electrically driven guinea pig auricle. This was the case when transmembrane potential measurements performed for an hour were averaged. If the data were evaluated in relation to time, a clear-cut biphasic effect of verapamil became obvious: in the period from 10 to 30 min after verapamil application a significant (5%) increase of RP and of Vmax (26%) could be seen; these changes became progressively slighter during the period from 30 to 50 min after verapamil application, while in the third phase (50 to 70 min) a significant decrease of both RP (11%) AND Vmax (27%) occurred in the guinea pig auricle. Similar kinetics of the verapamil effect were observed in the cat auricle. Verapamil at higher (3 microgram/ml) concentration decreased RP and Vmax. The time dependent dual effect of verapamil is probably unrelated to the inhibition of Ca conductivity as D 600, a more effective inhibitor in a corresponding dose (0.5 microgram/ml), failed to produce this type of time-dependent effect. A fourfold increase of Ca2+ concentration prevented the delayed depressing effect of 2 microgram/ml verapamil, but did not influence its early stimulating effect.

Action Potentials↗