Biomedical subjects

G A Mealing

Publications and source records attributed to G A Mealing.

24 records · Page 2Linked to original sources

PubMed1988

Evidence for two distinct potassium channels in avian granulosa cells.

Single-channel potassium currents were recorded in avian granulosa cells using the patch-clamp technique. Two types of channel were observed. The smaller of the two channels, gK1, had a conductance of 15 to 30 picosiemens (pS) and was voltage- and calcium-independent. Its null-current potential was -50 mV in the cell-attached recording mode. The other channel, gK2, was infrequently observed in the cell-attached configuration. Its conductance was between 160 and 195 pS. It could be activated by calcium on the cytoplasmic side of the membrane patch in the inside-out configuration. It was also voltage-dependent. These results suggest that fast transmembrane potassium movements may be involved in the membrane voltage regulation of granulosa cells, which in turn may play an important role in the modulation of steroidogenesis and other metabolic activities.

Animals↗

PubMed1985

[Programmable timer, counter of cycles of variable length and external events counter].

Explore the source record for details and available documents.

Electronics, Medical↗

PubMed1985

Dielectric properties of frog tissues in vivo and in vitro.

The relative permittivity and conductivity of blood, physiological saline, abdominal skin, skeletal muscle and heart of the bullfrog Rana Catesbeiana were measured at frequencies between 200 MHz and 8 GHz both in vivo and in vitro using an open-ended coaxial line probe in conjunction with an automatic network analyser. The results, when compared to published data on the dielectric properties of various tissues of the same and other species, indicate that: (i) the relative permittivity of frog skeletal muscle is similar to that of other species, except for the barnacle; (ii) the dielectric properties of frog heart are within the same range as for other species; (iii) differences exist between values obtained for heart in vivo and in vitro; and (iv) the dielectric properties of frog skin and blood compare well with those of human skin and blood.

Abdomen↗

PubMed1983

Evidence for functional sodium and calcium ion channels in the membrane of cultured cardiomyocytes of the adult rat.

Characteristics are reported for electrical activity of adult rat cardiomyocytes in long-term primary culture. Cells in vitro for 12 to 28 days have mean membrane potential of -53 mV, are electrically excitable, and some are spontaneously contractile. The action potential of these cells has a slow rate of depolarization and is abolished by methoxyverapamil (D-600) but not by tetrodotoxin (TTX). When cells are hyperpolarized by passage of an inward current, spontaneous action potentials cease and action potentials evoked by depolarizing pulses are then TTX sensitive. Fetal bovine serum is a constituent of the culture medium. Its temporary removal causes spontaneous contractility to cease but the cells remain electrically excitable.

Action Potentials↗

PubMed1980

A method for producing very low resistance micropipettes for intracellular measurements.

Using thin wall capillary tubing (1.0 mm O.D. x 0.75 mm I.D.) on an Industrial Science Associates puller, microelectrodes with approximately 4 times lower resistance than that of electrodes made from standard tubing (1.0 mm O.D. x 0.5 mm I.D.) can be achieved. This results in a factor of 2.7 improvement of electrode time constant. The advantages of the thin wall microelectrodes are obtained without sacrificing desirable tip dimensions and they represent a significant advance in microelectrode technology.

Animals↗

PubMedDate not supplied

An inexpensive portable incubator for tissue or cell cultures.

A lightweight incubator is described which is suitable for transporting cells or tissues maintained in Petri dishes. Since individual cultures are held in a sealed environment, sterility of samples is maintained, and pH remains stable for extended periods, even when bicarbonate buffered media is used. The incubator is battery powered, or may be connected to an automotive electrical power source. It has been designed to minimize exposure of the samples to mechanical shock. The components required for construction are inexpensive.

Culture Techniques↗