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Biomedical subjects

W Tuganowski

Publications and source records attributed to W Tuganowski.

At least 19 recordsLinked to original sources
PubMed1996

Inhibitory effects of O-benzyl-phosphocreatine ethyl ester in rabbit myocardium.

O-benzyl-phosphocreatine ethyl ester (BPC-EE) applied in superfusion evoked a negative chronotropic effect in the sinus node strips. The drug reduced the action potential amplitude and duration, decreased the resting potential, and diminished the isometric tension in the atrial trabeculae and papillary muscles. BPC-EE acted in a dose-dependent manner, and at 2.5 mmol/l it abolished the electrical phenomena in the examined preparations. BPC-EE lowered also the ATP and phosphocreatine content and decreased the creation kinase activity in ventricular specimens. The last finding is probably responsible for the remaining effects of BPC-EE.

Animals↗
PubMed1996

The effects of phosphocreatine introduced simultaneously into many cardiac cells.

The aim of the present study was to ascertain whether or not phosphocreatine (PC) could produce electrophysiological and inotropic effects in isolated rabbit cardiac preparations. Exogenous PC (50 mmol/l) was introduced into many cells simultaneously by the "cut-end" and "saponinated-end" methods. PC that entered the cells (opened by cutting or chemical disruption of the sarcolemma) in the loading region, passed through the preparation intercellularly and evoked the following effects in the test region. PC enhanced the spontaneous rate and probably shifted the pacemaker in sinus node strips. On the other hand, PC elevated the action potential amplitude and duration and increased the isometric tension in atrial and ventricular strips. Furthermore, PC applied into ventricular cells partially prevented the effects of hypoxia. These findings suggest that PC may act in cardiac muscle as an intercellular energy carrier. The effects of PC introduced intracellularly resembled these evoked by O-benzyl-phosphocreatine--a permanent synthetic phosphagen--applied via superfusion.

Animals↗
PubMed1994

Electrophysiologic and inotropic effects of O-benzyl-phosphocreatine in rabbit myocardium.

O-benzyl-phosphocreatine-Na (BPC) applied in superfusion increased the action potential amplitude and isometric tension in the isolated sinus node strips, atrial trabeculae and papillary muscles. BPC enhanced the slope of the slow diastolic depolarization evoking the positive chronotropic effect. The drug prolonged the action potential duration in the atrial and ventricular cells. BPC exerted similar effects during hypoxia and cyanide superfusion in the working myocardium. On the other hand, phosphocreatine as well as O-benzyl-phosphoglycocyamine added to the superfusion fluid were ineffective. BPC increased also the ATP content of the superfused contracting atrial trabeculae. These results suggest that BPC crosses the sarcolemma, elevates the ATP content, and thereby it increases the slow inward and can serve as an additional source of the metabolic energy in the cardiac cells.

Action Potentials↗
PubMed1991

Effects of calmidazolium, carbachol and derivatives of cyclic GMP on the longitudinal internal resistivity in rabbit atrial trabeculae.

The effects of calmidazolium, carbachol and membrane permeable derivatives of cGMP (dipalmitoyl cGMP and 8-Bromo cGMP) on the longitudinal internal resistivity (Ri) were studied in the rabbit atrial trabeculae by means of electrophysiological recording techniques and histological planimetry. Calmidazolium as well as carbachol decreased Ri whereas cGMP-derivatives enhanced this resistivity. The effect of calmidazolium suggested that calmodulin reduced the cell coupling under control conditions. Carbachol decreased the Ca-inward current, and probably it prevented the calmodulin activation. The action of the nucleotides showed that cGMP did not mediate the cholinergic effect on the cell coupling. The possible interaction between calmodulin and cGMP was discussed.

Animals↗
PubMed1989

Effects of calmidazolium and dibutyryl cyclic AMP on the longitudinal internal resistance in sinus node strips.

The effects of calmidazolium (10(-7) mol/l) and db cAMP (10(-3) mol/l) on the longitudinal internal resistance (ri) in the rabbit sinus node strips were studied by means of microelectrode and extracellular recording techniques. Calmidazolium (CDZ) decreased ri by 27%. An addition of db cAMP to the CDZ-containing Tyrode potentiated this effect by further 14%. db cAMP initially decreased ri by 17%, then it enhanced this resistance by 7% above the pretreatment control value. An addition of CDZ to the db cAMP-containing Tyrode reduced ri by 41% below the pretreatment control. Possible mechanisms underlying these effects were discussed in terms of cAMP, Cai, and calmodulin action on the cell coupling.

Animals↗
PubMed1986

A method of measurement of longitudinal resistances in an isolated cardiac and smooth muscle preparation.

The longitudinal internal as well as external resistance was measured by means of simultaneous intracellular and sucrose gap voltage recordings. The longitudinal internal resistance could be calculated from a formula comprising the shunt resistance, membrane action potential and transgap action potential before and after shunting. The longitudinal external resistance was calculated from another formula comprising the same quantities.

Animals↗
PubMed1981

Mechanism of intercellular synchronization in the rabbit sinus node.

A strip of tissue cut from the sinus node, 0.5 mm wide, was studied in a sucrose gap chamber. With the gap width of 0.6--1.5 mm the 2 ends of the preparation showed nonsynchronous activity. Synchronization could be re-established by a shunt resistor, 15--100 k omega, connected across the gap, suggesting that synchronous firing of the sinus node requires local circuit currents.

Action Potentials↗
PubMed1980

Effect of histamine in sinus node arrested with reserpine.

Histamine restored spontaneous activity in the isolated rabbit sinus node arrested with reserpine. This fact suggests that catecholamines are not the unique activators of adenylate cyclase required for cardiac pacemaking, and may be replaced by histamine.

Adenylyl Cyclases↗
PubMed1978

The effect of cGMP in rabbit auricle as studied by a cut-end method.

Cyclic GMP was applied to the rabbit right auricle by a cut-end method. The nucleotide decreased the spontaneous rate, hyperpolarized the cell membrane and reduced the amplitude and the slow component of the action potential. It also decreased the force of contraction. These results suggest that cGMP may be the mediator of the action of acetylcholine in the rabbit auricle.

Action Potentials↗
PubMed1977

Iontrophoretic application of autonomic mediators and cyclic nucleotides in the sinus node cells.

The effects of intracellular application of noradrenaline, acetylcholine, cAMP and cGMP were studied in the sinus-node of the rabbit. Noradrenaline and acetylcholine were without effect on electrical activity. In about one third of cases, cAMP increased, and cGMP decreased the slope of slow depolarization. These results suggest that adrenergic as well as cholinergic receptors which control the electrical activity of the sinus node cell are localized at the outer side of the cell membrane. It has also been shown that the cyclic nucleotides exert direct but opposite chronotropic effects.

Acetylcholine↗
PubMed1977

The influence of adenylate cyclase inhibitors on the spontaneous activity of the cardiac pacemaker.

The effects of adenylate cyclase inhibitors, haloperidol and chlorpromazine, on the spontaneous activity of the rabbit sinus node was studied by means of double sucrose gap and intracellular microelectrodes. Haloperidol and chlorpromazine arrested the spontaneous activity which could be restored with noradrenaline, in the presence of haloperidol, or with dibutyryl c AMP, in the presence of either inhibitor used. After arresting of the spontaneous activity, sinus node cells might utilize metabolic energy supplied from exogenous pyruvate. Pyruvate protected from depolarization or reestablished polarization in depolarized cells but was not able to restore the spontaneous activity. Discussion of these results suggests that c AMP may be directly involved in the spontaneous electrogenesis in the sinus node.

Adenylyl Cyclase Inhibitors↗
PubMed1975

Glycogen content in human embryonic heart.

Glycogen concentration in the human embryonic heart is about 10 times higher than in that of human adults. Glycogen content of embryonic right atrium is significantly higher than that in ventricles.

Female↗