PubMed Health⌕ Search

Biomedical subjects

S D Erulkar

Publications and source records attributed to S D Erulkar.

48 records · Page 3Linked to original sources
PubMed1973

The action of calcium at spinal neurones of the frog.

1. The action of Ca on membrane excitability and synaptic transmission at motoneurones of the isolated spinal cord of the frog has been studied.2. Impulse propagation along presynaptic fibres was unaffected by [Ca] in the range of 0-10 mM in the presence of 1 mM-Mg.3. Motoneurone membrane excitability was within normal ranges when the cord was bathed in low or 0 Ca solutions containing 1 mM-Mg but was depressed in 5 or 10 mM-Ca solutions.4. Spontaneous miniature synaptic potentials were recorded in the presence of tetrodotoxin. The frequencies were reduced but not abolished in the absence of bath Ca, but were increased greater than twofold in 5 or 10 mM-Ca in comparison to those in normal Ringer solution (1 mM-Ca).5. Iontophoretic application of Ca both near to and remotely from the intracellular recording site (presumably in the soma) caused facilitation of elicited post-synaptic potentials.6. It is concluded that the action of Ca at these central synapses is identical to that described at the neuromuscular junction.

Action Potentials↗
PubMed1968

Intracellular recording from mammalian superior cervical ganglion in situ.

1. Recordings have been obtained by intracellularly placed microelectrodes from cells of the superior cervical ganglion of the rabbit. The ganglion was left in situ.2. In response to stimulation of the external carotid nerve, some cells responded with a single spike of short latency followed by a long-lasting hyperpolarization. These cells, presumably, were activated antidromically. The majority of cells, however, responded with an early spike followed by a long-lasting depolarization; superimposed on this depolarization were one or two spikes with latencies from 35 to 70 msec. Anatomical pathways responsible for this activation have been suggested.3. A variety of responses were recorded from different neurones when the preganglionic sympathetic trunk was stimulated. Many of the cells responded to maximal stimulation of the nerve with repetitive spikes. Stimuli of constant strength could elicit variable responses from a single neurone. This variability and the multiple spike response may be due to multiple pathways leading to the same cell and the possibility of the presence of internuncial neurones in the ganglion is suggested.4. Strong stimulation of the preganglionic sympathetic nerve trunk caused inhibitory effects at the ganglion cells.5. Direct stimulation of the ganglion cells through the recording microelectrode elicited only one spike even at high intensity. Thus the multiple spike response to orthodromic stimulation must have been due to a temporally dispersed afferent input.6. It is concluded that the organization of the rabbit superior cervical ganglion is more complex than has been suspected previously, and that integration as well as transmission takes place at the level of these neurones.

Animals↗
PubMed1968

Miniature synaptic potentials at frog spinal neurones in the presence of tertodotoxin.

1. Spontaneous subthreshold potentials have been recorded with an intracellular electrode from neurones of the isolated spinal cord of the frog.2. Records of both depolarizing and hyperpolarizing potentials were obtained from cells in normal Ringer solution and also when impulse conduction in the cord had been abolished by tetrodotoxin (TTX).3. Comparisons of results before and after TTX show that the majority of the spontaneous potentials are analogous to miniature end-plate potentials.

Animals↗