Potential differences between normal nodes of Ranvier (single fiber from the sciatic nerve of the frog, air-gap method) and a node exposed to 1 to 2.5 x 10(-6) gm veratridine per ml were measured. Negative after-potentials occurred immediately after application of the alkaloid when spike configuration and resting potential were virtually unchanged. The after-potentials decreased in magnitude and their time constant increased as the resting membrane was depolarized either by outward currents or by a train of impulses. Increase of (Na)(o) markedly increased the amplitude of the after-potential. After prolonged application of veratridine or with higher concentrations, a large slow depolarization (rate of potential change about 7 mv per second) could be triggered by a train of impulses or even a single spike. This depolarization could promptly be terminated by withdrawing Na. It is concluded that, once the nodal membrane has become permeable to Na (as during a spike), veratridine prevents the normal return of P(Na) to its resting value.

Animals↗

PubMedDate not supplied

[Behavior of the volume and number of fat cells in obese patients in middle age in inpatient weight reduction].

Fat cell volume and fat cell quantity were determined in subcutaneous fatty tissue of 27 obese patients (22 female and 5 male aged 42 +/- 8) before and after in-patient weight reduction. 47 normal probands of the same age served as a control group. With in-patient weight reduction, fat cell volume decreased significantly, while fat cell quantity remained constant. Division of obesity into hypertrophical and hypertrophical-hypercellular types based on fatty tissue cellularity is suggested. Possible indication for the determination of fat cell volume in obese patients is shown.

Adipose Tissue↗