Spontaneous Bioelectric Activity Research Articles

Calcium uptake and bioelectrical activity of denervated and myotonic muscle.

Calcium uptake on muscle microsomal fraction has been investigated in connection with bioelectrical activity in some muscle diseases. The findings showed a significant increase of calcium uptake in denervated muscle, which exhibited spontaneous bioelectrical activity (fibrillations). In myotonias, a low calcium uptake was peculiar to Steinert's disease but not to myotonia congenita. In other muscle diseases, such as progressive muscular dystrophy (Duchenne's type) or Charcot-Marie-Tooth's disease, the ability of muscle microsomal fraction to bind calcium was not changed. Starting with the key role of calcium in excitation-contraction coupling, the implications of calcium uptake disturbances in muscle electrogenesis are discussed.

Note on the ganglionic and central actions of galantamine.

Abstract The actions of galantamine on ganglionic transmission in the superior cervical ganglion of the cat and the spontaneous bioelectrical activity of the brain were investigated and compared with those of physostigmine. Galantamine prevented ganglionic blockade due to C 6 more strongly than physostigmine and increased ganglionic depolarization induced by acetylcholine. This compound caused periodic asynchronous postganglionic firing in the cat superior cervical ganglion. It is suggested that the mechanism of action of galantamine resembles that of neostigmine rather than that of physostigmine and is not limited to the excitation of “muscarinic cholinoceptive sites” alone. Galantamine administered intravenously in unanaesthetized cats caused a marked desynchronization of cortical and subcortical electrical activity, which was completely abolished by atropine or benactyzine.

The effect of anion substitution on bioelectric potentials in the moth heart

1. 1. Transmembrane potentials in single cells of the moth myocardium were measured during exposure to physiological bathing solutions in which the chloride content was completely replaced with a series of anions (acetate, nitrate, bromide and sulfate) of varying molecular size known to exhibit varying degrees of penetrability in vertebrate muscle fibers. 2. 2. The degree of penetrability of these anions was assessed according to the transient and long-term effects produced on spontaneous bioelectric activity. 3. 3. Both acetate and sulfate solutions produced cardiac standstill, acetate by hyperpolarization of the membrane and sulfate by depolarization of the membrane. A transient slowing followed by an increase in spontaneous heartbeat frequency resulted from nitrate solution. Bromide solution had little if any effect. 4. 4. This evidence suggests that the order of penetrability of these anions is acetate > nitrate > bromide > chloride. The membrane is impermeable to sulfate.

Morphological and physiological properties of neurons and glial cells in tissue culture.

Morphological and physiological properties of neurons and glial cells in tissue culture.