Biomedical subjects

G Sedek

Publications and source records attributed to G Sedek.

22 records · Page 2Linked to original sources

PubMedDate not supplied

A new approach to the direct measurement of tension within the outer layers of the left ventricular wall of the dog heart.

Tension was measured within the outer layers of the left ventricular wall of the dog heart with the strain-gauge force transducer coupled to the wall at diastole without the distortion of its geometry. The transducer still attached to the wall or its segments was calibrated with the passive forces and with the known active force on the isolated, beating heart. The differences between the readings of the transducer and the calibrating force did not exceed 20% and in most experiments they were much smaller. The transducer was practically insensitive to the force perpendicular to the measured one. The proposed method seems to be more reliable than the formerly used by these and other authors.

Animals↗

PubMedDate not supplied

Evaluation of extravascular resistance in the unloaded fibrillating left ventricle of the dog.

In open-chest anaesthetized dogs the relative magnitude of extravascular resistance in the superficial and deep left ventricular myocardium was estimated from the flow through the isolated vascular segments inserted at different depths of the myocardium. It was confirmed that in the normally working heart extravascular resistance was significantly greater in the deep than in the superficial layer. In the unloaded fibrillating left ventricle no difference in extravascular resistance between these layers could be detected. Since it had been found previously that subendocardial preponderance of ischaemia persists in the unloaded fibrillating left ventricle (Sedek and Michałowski, submitted for publication), the present observation is a further challenge for the current view that the subendocardium is more vulnerable to ischaemia because extravascular resistance is greater in this layer.

Animals↗

PubMedDate not supplied

Inotropic and electrophysiological effects of AB--2, a new antiarrhythmic agent, on isolated cardiac preparations.

Effects of AB--2, a compound structurally related to quinidine, on the force of contraction and intracellular potentials were studied in isolated cardiac preparations obtained from guinea pigs, rabbits, cats and dogs. AB--2 in concentrations of 3 and 6 microM increased the force of contraction of both ventricular and atrial muscle. This effect was absent in reserpinized preparations. In concentrations of 24-96 microM, AB--2 induced a concentration-dependent depression of contraction (ED50 approximately equal to 55 microM). Electrophysiological effects consisted of: 1) concentration-dependent reduction of maximum rate of depolarization (Km for guinea pig ventricular and atrial muscles was 72 and 111 microM, resp.) with no change in the resting membrane potential; 2) shortening of action potential duration in ventricular and Purkinje fibers while prolongation in atrial muscle; 3) reduction of pacemaker activity in Purkinje fibers. It is concluded that electrophysiological effects of AB--2 are similar to those of Class I antiarrhythmic agents.

Action Potentials↗

PubMedDate not supplied

Influence of surgery and experimental myocardial infarction on blood levels of free fatty acids and triiodothyronine in dogs.

Preparatory operations (PO) including thoracotomy have been performed in 11 dogs. After 6 days in 6 dogs the left anterior descending coronary artery (LAD) was ligated leading to development of acute myocardial infarction (MI). Both after PO and during MI and increase in plasma free fatty acids (FFA) and a decrease in serum triiodothyronine (T3) was observed. There was a negative correlation between T3 and FFA 4--22 hours after PO and 9--22 hours after LAD ligation. In control dogs without LAD ligation a positive correlation between FFA and T3 levels was shown 8--18 days after PO during the period of wound healing. It seems that the combination of elevated FFA and depressed T3 reflects the metabolic disturbances which are more pronounced during MI than after surgical operation connected with thoracotomy.

Animals↗