Linked Life Data

932635

Source:http://linkedlifedata.com/resource/pubmed/id/932635

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1976-9-1
pubmed:abstractText
The straited myoepithelial cells of the proventriculus of Syllis spongiphila are composed of only one or two sarcomeres that may reach 40 mum in length. Experiments were performed to study some of their electrophysiological properties and their synaptic control. The mean resting potentials recorded in two different bathing media were 59-1 +/- 5-5 mV (S.D., n=91) and 62-5 +/- 6-3 mV (S.D., n=98). At rest the membrane potential is determined largely by permeability of the membrane to K+ ions, but the membrane is also permeable to other ions. On a semilogarithmic plot of membrane potential v. [K]o the mean slope of the data points from 9 to 90 mM-[K]o was 48 +/- 3 mV for a 10-fold change in [K]o. The anterior end of the animal was stimulated with a suction electrode to elicit activity of nerve fibres that innervate the proventriculus. Single indirect stimuli usually evoked hyperpolarizing or biphasic responses, and occasionally depolarizing responses, from the myoepithelial cells. The depolarizing synaptic potentials exhibited a faster time course than the hyperpolarizing ones. The rise time to peak ranged from 20 to 35 ms for simple depolarizations (n=32) and 25-75 ms for simple hyperpolarizations (n=103). Time to decay to half amplitude ranged from 20 to 55 ms for depolarizations (n=29) and 62-135 ms for hyperpolarizations (n=87). Low frequency (is less than or equal to 4 Hz) trains of indirectly applied stimuli elicited mainly hyperpolarizing responses; higher frequency (5-40 Hz) trains elicited complex responses composed of hyperpolarizations and depolarizations. Hyperpolarizations were selectively and reversibly abolished in chloride-free solutions. The reversal potential of the hyperpolarizing synaptic potential was -104 +/- 3 mV (S.D., n=8, 2 preparations). In calcium-free solution both hyperpolarizations and depolarizations were almost completely abolished. 4 mM-Mn2+ added to the bath almost completely abolished the depolarization but not the hyperpolarization. It was not clear whether Mn2+ acted at the presynaptic membrane, the postsynaptic membrane or both. The myoepithelial cells are electrically coupled. The mean space constant of five preparations was 0-52 mm (range 0-40-0-66 mm).
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0022-0949
pubmed:author
pubmed:issnType
Print
pubmed:volume
64
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
691-710
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed:year
1976
pubmed:articleTitle
Electrical activity of the proventriculus of the polychaete worm Syllis spongiphila.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.