The pacemaker activity of the S-A node cell was explained by reconstructing the pacemaker potential using a Hodgkin-Huxley type mathematical model which was based on the reported voltage clamp data. In this model four dynamic currents, the sodium current iNa, the slow inward current, is, the potassium current, iK, and the hyperpolarization-activated current, ih, in addition to a time-dependent ...

The objective of this study was to determine the effects of 3 chemical agents used sequentially and electrical stimuli on parthenogenetic activation of in vitro matured bovine oocytes and comparison with a standard IVF protocol for embryo developmental rates. For this purpose, oocytes were matured in tissue culture medium-199 (TCM-199) at 39 °C and 5% of CO2 in humidified air. For IVF, matured ...

Adenosine, an important regulator of many cardiac functions, is produced by ectosolic and cytosolic 5'-nucleotidase. The activity of these enzymes is influenced by several ischemia-sensitive metabolic factors, e.g., ATP, ADP, H+, and inorganic phosphate. However, there is no clear evidence that adenosine itself affects 5'-nucleotidase activity. This study tested whether adenosine decreases the ...

The heat liberated upon stress production in isolated cardiac muscle provides insights into the complex thermodynamic processes underlying mechanical contraction. To that end, we simultaneously measured the heat and stress (force per cross-sectional area) production of cardiac trabeculae from rats using a flow-through micromechanocalorimeter. In a flowing stream of O(2)-equilibrated Tyrode solu...

Electrical activities have been recorded in a preparation consisting of the pelvic region and the upper ureter of the guinea pig. Train field stimulation of the pelvic region evoked a train of nerve action potentials followed by a multiphasic smooth muscle action potential after a latency of about 2.5--8.0 sec. This smooth muscle response was abolished by tetrodotoxin and dibucaine, and also by...

A method has been described by which it is possible to estimate the number of particles of vaccine virus which are required to cause infection in the rabbit skin. The method consists essentially in performing a series of intradermal inoculations in rabbits of suitably diluted virus suspensions. The percentage of inoculations at each dilution giving rise to lesions is observed, and the data are ...

Stiffness of live cardiomyocytes isolated from control and diabetic mice was measured using the atomic force microscopy nanoindentation method. Type 1 diabetes was induced in mice by streptozotocin administration. Histological images of myocardium from mice that were diabetic for 3 mo showed disorderly lineup of myocardial cells, irregularly sized cell nuclei, and fragmented and disordered myoc...

Right atria from excised beating dog hearts were immersed in Tyrode solution with the endocardial surface of the anterior wall exposed. Glass microelectrodes were used to impale fibers in different anatomical areas of this preparation. Fibers with action potentials similar in contour to those of ventricular Purkinje fibers were found along the caval border of the crista terminalis in the area o...

Nicholls, P. J., Evans, E., Valic', F., and ;uskin, E. (1973). British Journal of Industrial Medicine, 30, 142-145. Histamine-releasing activity and bronchoconstricting effects of sisal. Extracts of dry and oiled sisal released histamine from pig and human but not from rat lung tissue. A suspension in Tyrode solution of the oil used for softening the sisal fibres had a pH of 8-1 and also releas...

GOODALE, ROBERT L., BOYD GOETZMAN, AND MAURICE B. VISSCHER. Hypoxia and ioduacetic acid and alveohzpillary barrier permeability to albumin, Am. J. Physiol. 219(5): 12264230. 1970Perfusion studies at controlled flow rates using the isolated left lower lobe of the canine lung were performed under normal oxygen tensions and under conditions of low 0, tension, averaging 12 mm Hg. The average permea...