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Biomedical subjects

J Borbola

Publications and source records attributed to J Borbola.

27 records · Page 2Linked to original sources

Application of His bundle recording in different rhythm disturbances of the heart.

The new intracardiac electrophysiological method: His bundle electrocardiography, combined with the electrophysiological examination used in routine clinical practice, has considerably improved our knowledge of the cardiac dysrhythmias. It helps to localize the focus of the atypical junctional and other supraventricular premature beats complicated with either organic or functional intraventricular conduction disturbance. The various forms of paroxysmal tachycardias can be differentiated more exactly from each other. In pre-excitation syndrome, it has become possible to detect the abnormal pathway and to screen the patients susceptible to life-threatening arrhythmias. By means of this the diagnosis of sick sinus syndrome and estimation of its severity can be made more exactly. In addition to the diagnosis, the electrophysiological examinations connected with pharmacological tests give valuable information whether medical or pacemaker therapy should be applied. Six cases of various forms of cardiac dysrhythmias are presented to demonstrate the superiority of this method.

Adult↗

The effects of arachidonic acid in isolated atria of guinea pigs.

The effects of free and albumin-bound arachidonic acid, which is the precursor of the prostaglandins E2 and F2alpha, were studied on the spontaneous rate, contractile force and myocardial fatty acid metabolism in isolated, spontaneously beating atria of guinea pigs. Both free and albumin-bound arachidonic acid (10(-6)-10(-3) M) produced a dose-dependent positive chronotropic and a modest inotropic action. Tachyphylaxis to the positive chronotropic action of arachidonic acid developed in the course of repeated applications. Beta-Adrenoceptor blockade (pincolol) and pretreatment with reserpine or prostaglandin-synthetase inhibitors (indomethacin, fenoprofen, aspirin, 5,8,11,14-eicosatetraynoic acid) failed to affect the chronotropic activity of arachidonic acid significantly. The action of arachidonic acid was independent of the decarboxylation of the fatty acid. Linoleic and oleic acids did not show any positive chronotropic activity. The data are interpreted as suggesting that changes induced by arachidonic acid might be partly due to peroxides formed from arachidonic acid.

Animals↗

Cardiac actions of arachidonic acid.

The cardiac actions of arachidonic acid (AA, C 20:4), the precursor of prostaglandin E2 (PGE2) and F2 alpha (PGF2 alpha) were studied in isolated atria and papillary muscles of guniea-pigs as well as canine Purkinje fibers. In contrast to the cardio-depressant actions of some short and long-chain fatty acids (octanoate, oleate) AA (10(-6)-10(-4) M) increased sinoatrial rate and contractility in guinea-pig atrial preparations. This cardio-stimulant action of AA was accompanied by an increase in the amplitude and maximum rate of rise of the intracellularly recorded atrial action potential. Some increase in the resting membrane potential and a slight prolongation of the action potential duration could also be observed. AA did not induce any pace-maker activity in isolated papillary muscle of guinea pigs or in isolated Purkinje fibers. Similarly to AA, PGE2 and PGF2 alpha (2.1-10(-8)12.1-10(-5) M) were also found to increase atrial rate and contractile force. The stimulating actions of AA were reduced by application of high concentrations of indomethacin (5-10(-5) M).

Action Potentials↗