To investigate cardiac stunning, we recorded intracellular [Ca(2+)], contractions, and electrical activity in isolated guinea pig ventricular myocytes exposed to simulated ischemia and reperfusion. After equilibration, ischemia was simulated by exposing myocytes to hypoxia, acidosis, hyperkalemia, hypercapnia, lactate accumulation, and substrate deprivation for 30 min at 37 degrees C. Reperfusi...

Kohzuki, Hisaharu, Hiromi Misawa, Susumu Sakata, Yoshimi Ohga, Hiroyuki Suga, and Miyako Takaki. Energy expenditure by Ba21 contracture in rat ventricular slices derives from cross-bridge cycling. Am. J. Physiol. 276 (Heart Circ. Physiol. 45): H74–H79, 1999.—To clarify the energy-expenditure mechanism during Ba21 contracture of mechanically unloaded rat left ventricular (LV) slices, we measured...

One of the undesired complications of the chemotherapy with doxorubicin is cardiotoxicity. Cardiac effect of erucic acid, which is a member of omega-9 fatty acid, is investigated on doxorubicin treatment in this study. Forty-eight rats were divided into eight groups and each group contained six rats. First group rats were fed with milk. In the third and fifth groups we fed rats with milk supple...

To clarify the energy-expenditure mechanism during Ba2+ contracture of mechanically unloaded rat left ventricular (LV) slices, we measured myocardial O2 consumption (V˙o 2) of quiescent slices in Ca2+-free Tyrode solution andV˙o 2 during Ba2+ contracture by substituting Ca2+ with Ba2+. We then investigated the effects of cyclopiazonic acid (CPA) and 2,3-butanedione monoxime (BDM) on the Ba2+ co...

Close platelet-to-platelet contact induced by weak agonists in a medium with a low concentration of Ca2 leads to thromboxane A2 (TXA2) formation, release of granule contents. and secondary aggregation. These responses do not occur in a medium containing Ca2 in the physiological range (1 to 2 mmol/L). Experiments were done to determine whether feedback amplification is required to generate amoun...

Small trabeculae of rabbit left atrium immersed in TKBa solution (Tyrode with 10 mM K+ and 1 mM Ba2+) were used to study frequency dependence of "membrane" slow response excitability at long cycle lengths (>1 s) . In TKBa, stimuli generate graded, low-amplitude (2-15 mV) subliminal responses of variable long duration (up to 450 ms) . A full all-or-none slow response is generated when a sublimin...

Because of its electrophysiological effects, hypothermia can influence the mechanisms that intervene in the sustaining of ventricular fibrillation. We hypothesized that a rapid and profound reduction of myocardial temperature impedes the maintenance of ventricular fibrillation, leading to termination of the arrhythmia. High-resolution epicardial mapping (series 1; n = 11) and transmural recordi...

Prekallikrein (PK) activation on human umbilical endothelial cells (HUVEC) presumably leads to bradykinin liberation. On HUVEC, PK activation requires the presence of cell-bound high-molecular-weight kininogen (HK) and Zn(2+). We examined the Zn(2+) requirement for HK binding to and the consequences of PK activation on endothelial cells. Optimal HK binding (14 pmol/10(6) HUVEC) is seen with no ...

A method has been described by which whole cells may be separated from the thymus tissue of rats. Cells obtained by this method have been found capable of incorporating leucine, valine, glycine, and alanine (labeled with C x4 in the carboxyl position) a t a rate equal to or slightly higher than that observed in slices of thynms tissue, in Yoshida ascites tumor cells from the rat, and in Ehrlich...

We tested the hypothesis that sildenafil, singly or in combination with nitric oxide (NO) donors, promotes ventricular tachycardia (VT) and ventricular fibrillation (VF). Vulnerability to VT/VF was tested by rapid pacing in eight isolated normal swine right ventricles (RV). The endocardial activation was optically mapped, and the dynamic action potential duration (APD) restitution curves were c...