[Contractility of the left ventricle of the human heart noninvasive measurement in each cardiac cycle].

History of development of the method of measurement of duration of the preejection (DPE) period - characteristic of left ventricular (LV) contractility is presented. On the basis of physiological prerequisites a novel computerized method of DPE measurement in each consecutive cardiocycle has been created. Distinct features of this method are: 1) principle of measurement - tetrapolar impedancemetry, with signal electrodes located along projection of the ascending aorta, one in the center of presternum, second - 5 cm caudally; 2) starting point for DPE counting - the point on ascending portion of R wave of electrocardiogram at which the first derivative of ECG signal reaches maximum, stopping point - the point of maximum of the second derivative of the primary impedance signal on the ascending front of its pulse wave.

[Pre-ejection period as a cardiac cotractility index: noninvasive beat-by-beat evaluation in the human study].

Beat-by-beat evaluation of left ventricular contractility provides and insight to the current dynamics of cardiac control. In non-invasive studies, pre-ejection period is conventionally used as an index of contractility. Pulse waves of electrical impedance (deltaZ) reflect the systolic dilations of the aorta segment confined between the properly placed signal electrodes.

Antidromic vasodilation in frog: identification of the nerve fiber types involved.

In anesthetized, immobilized frogs arteriolar vasodilation in the submaxillaris muscle in response to electrical stimulation of the submaxillar nerve (peripheral end) was observed directly and vasodilation in the hind leg in response to stimulation of the sciatic nerve (peripheral end) measured by plethysmography. With pulses of 0.1 ms duration at 20 Hz, the threshold for arteriolar vasodilation in the submaxillaris muscle was close to 3 T, where T was the activation threshold of the most excitable fraction of motor fibers of the submaxillar nerve.

[An experimental verification of the histomechanical theory of the working hyperemia of the skeletal muscles: biomicroscopic research].

The histomechanical hypothesis of working hyperemia in skeletal muscle was verified by comparison of the dynamics and values of frog submaxillary muscle arterioles dilation under: 1) 4-Hz twitch contraction and 2) imitation of mechanical component of the twitch contractions. Deformation of arterioles occurred during incomplete tetanus with the maximal effect at the peaks of twitches. The repetitive displacements of a small bunch of muscle fibers with the frequency of 4 Hz and the amplitude of 0.

The dilation of arterioles in frog submaxillaris muscle caused by visible light.

Transillumination of submaxillaris muscle with incandenscent lamp led to arteriolar dilation if the illuminance exceeded 1-2 x 10(3) lux or reached the time-mean value of 3 x 10(4) lux when a flash lamp was used (pulse duration 10 microseconds, repetition rate 50 s-1). The temperature increase within a light spot on the muscle did not exceed 0.1 degrees C, visible light being the only reason of the dilation of arterioles.