+ Site Statistics
+ Search Articles
+ Subscribe to Site Feeds
Most Shared
PDF Full Text
+ PDF Full Text
Request PDF Full Text
+ Follow Us
Follow on Facebook
Follow on Twitter
Follow on LinkedIn
+ Translate
+ Recently Requested

Membrane excitability in the neurohypophysis

Membrane excitability in the neurohypophysis

Advances in Experimental Medicine and Biology 449: 193-200

The application of patch clamp technology to the neurohypophysis has contributed significantly to our understanding of the membrane events governing neuropeptide secretion. Nerve terminals within the posterior pituitary are now known to contain three distinct K+ channel subtypes, a rapidly inactivated channel (responsible for A current), a Ca(2+)-activated K+ channel, and a delayed rectifier channel. Activation of a D2 subtype dopamine receptor reduces both the A-current and current through the Ca2+ activated K+ channels. These actions can be expected to enhance neuropeptide release. Release of nitric oxide reduces the amplitude of the A-current but enhances current through the Ca(2+)-activated K+ channel, and this would provide mechanisms for more complex modes of regulation of release. Neurohypophysial nerve terminals also express at least two types of Ca2+ channels. The first is a dihydropyridine-sensitive, "L-type" channel. The second resembles the "N-type" Ca2+ channel. Patch clamp recordings have shown that tissue culture medium conditioned by exposure to T-cells enhances this Ca2+ current. This may represent a mechanistic link between activation of the immune system and functional membrane changes within the neurohypophysis. GABA-activated Cl- channels have also been described within the neurohypophysis, and these receptors can be modulated by neuroactive steroids. One of these, the progesterone derivative allopregnanolone, changes dramatically during female reproductive transitions. Such an interaction could represent a pivotal mechanistic step in the onset of parturition, and the neurohypophysial GABA receptor may hold promise as a target of therapeutic intervention in clinical cases of preterm labor.

(PDF emailed within 1 workday: $29.90)

Accession: 046661367

Download citation: RISBibTeXText

PMID: 10026805

Related references

Effects of raised extracellular potassium on the excitability of, and hormone release from, the isolated rat neurohypophysis. Journal of Physiology 399: 591-605, 1988

Activity-dependent depression of excitability and calcium transients in the neurohypophysis suggests a model of "stuttering conduction". Journal of Neuroscience 23(36): 11352-11362, 2003

Membrane vesiculation at sites of exocytosis in the neurohypophysis, adenohypophysis and adrenal medulla: a device for membrane conservation. Journal of Physiology 218 Suppl: 94p-95p, 1971

Membrane potential of the muscle as a determining factor of excitability. I. Influence of chlorides on membrane potential and on excitability of the frog's sartorius muscle. II. Action of hypertonic Ringer's fluid on membrane potential and on excitability of sartorius muscle of the frog. III. Action of carbon dioxide on the frog's sartorius muscle. IV. Effect of fatigue due to prolonged stimulation on the frog's sartorius muscle. V. Effect of glucose-Ringer's fluid and e. Japanese Jour Mad Sci Iii Biophysics 3(1): 1-15, 16-23, 25-34, 35-40, 41-44, 45-48, 49-53, 1934

Demonstration of reversible membrane internalization after exocytosis in the rat neurohypophysis. Neuroscience Letters 104(3): 292-297, 1989

Part 1 || Antibodies to the Ciliary Membrane of Paramecium tetraurelia Alter Membrane Excitability. Journal of Cell Biology 97(5): 1421-1428, 1983

Antibodies to the ciliary membrane of Paramecium tetraurelia alter membrane excitability. Journal of Cell Biology 97(5 Pt 1): 1421-1428, 1983

The correlation between the lateral motion of membrane lipids and nerve membrane excitability. Biomedical Research (Tokyo): 7(Suppl.): 49-51, 1986

Excitability of squid axon membrane in the absence of ion-concentration gradient across the membrane. Upsala Journal of Medical Sciences 85(3): 217-224, 1980

Membrane excitability and membrane currents in the marine ciliate Euplotes vannus. European Journal of Protistology 24(1): 11-21, 1988

Reversal of potential across a liquid non-aqueous membrane with regard to membrane excitability. Nature 207(5001): 1045-1047, 1965

Excitability of artificial membrane as an analogy to excitable biological membrane. Annals of the New York Academy of Sciences 195: 457-480, 1972

Effects on the isolated neurohypophysis of agents which affect the membrane permeability to calcium. Journal of Physiology 231(2): 96p-98p, 1973

Specific arrangements of membrane particles at sites of exo-endocytosis in the freeze-etched neurohypophysis. Cell and Tissue Research 165(3): 317-325, 1976

Relationship between membrane depolarization and intracellular free calcium in individual nerve terminals from the neurohypophysis. Annals of the New York Academy of Sciences 635: 441-442, 1991