Activity-dependent change in morphology of the glial tubular lattice of the crayfish medial giant nerve fiber.

An evaluation of electron micrographs of stimulated nerve fibers used to investigate the effect of action potential generation on the structure-function relationship between axons and its associated glial cells revealed that what was at first thought to be stimulation-induced damage to the glia was, in fact, limited to volume expansion and disaggregation of the glial tubular lattice. All other structures appeared well preserved and otherwise normal. Using a 4-point subjective scale for evaluation by two investigators, 50-Hz stimulation for 2 min was observed to cause a volume expansion and disaggregation of the tubular lattice.

Effect of ouabain on adenosine receptor-mediated hyperpolarization in porcine coronary artery smooth muscle.

We investigated the effect of inhibitors of endothelium-derived nitric oxide and sodium-potassium (Na(+)-K+) pumps on adenosine receptor-mediated hyperpolarization of porcine coronary artery smooth muscle with and without endothelium. The average resting membrane potential (RMP) in porcine coronary artery smooth muscle was -51.5 +/- 0.

Glutamine cycle enzymes in the crayfish giant nerve fiber: implications for axon-to-glia signaling.

Two of the key enzymes involved in glutamate metabolism, glutaminase and glutamine synthetase, were quantitatively localized to axons and glia of the crayfish giant nerve fiber by immunocytochemistry and electron microscopy of antibody-linked gold microspheres. In Western blots, rabbit antisera for glutamine synthetase and glutaminase specifically recognized crayfish polypeptides corresponding approximately in size to subunits of purified mammalian brain enzymes. Glutamine synthetase immunoreactivity was found to be 11 times greater in the adaxonal glial cells than in the axon.

Role of endothelium in hyperpolarization of coronary smooth muscle by adenosine and its analogues.

We studied the effects of adenosine (AD) and its analogues, 5'-N-ethylcarboxamidoadenosine (NECA) and 2-chloroadenosine (CAD) on membrane potential of porcine coronary artery with an without endothelium, conducting experiments with addition of indomethacin (10(-5) M) to rule out involvement of prostanoids. Average resting membrane potential (RMP) in porcine coronary artery was -51.1 +/- 0.