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Titolo:
ELECTRICAL-PROPERTIES OF SMOOTH-MUSCLE IN THE GUINEA-PIG URINARY-BLADDER
Autore:
BRAMICH NJ; BRADING AF;
Indirizzi:
UNIV MELBOURNE,DEPT ZOOL PARKVILLE VIC 3052 AUSTRALIA UNIV OXFORD,DEPT PHARMACOL OXFORD OX1 3QT ENGLAND
Titolo Testata:
Journal of physiology
fascicolo: 1, volume: 492, anno: 1996,
pagine: 185 - 198
SICI:
0022-3751(1996)492:1<185:EOSITG>2.0.ZU;2-6
Fonte:
ISI
Lingua:
ENG
Soggetto:
EXCITATORY JUNCTION POTENTIALS; OMEGA-CONOTOXIN GVIA; VAS-DEFERENS; NEUROMUSCULAR-TRANSMISSION; NERVE-STIMULATION; ARTERIOLES; ATP; MEMBRANE; RABBIT; CELLS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
40
Recensione:
Indirizzi per estratti:
Citazione:
N.J. Bramich e A.F. Brading, "ELECTRICAL-PROPERTIES OF SMOOTH-MUSCLE IN THE GUINEA-PIG URINARY-BLADDER", Journal of physiology, 492(1), 1996, pp. 185-198

Abstract

1. The effects of transmural nerve stimulation were examined on preparations of detrusor smooth muscle from guinea-pig urinary bladder using intracellular recording techniques. Most recordings were made from preparations in which spontaneous and evoked action potentials had beeninhibited by nifedipine (10 mu M), a dihydropyridine that blocks L-type Ca2+ channels. 2. Supramaximal stimuli evoked excitatory junction potentials (EJPs) which could be divided into three basic types. Type 1EJPs had short latencies (<30 ms) and fast rise times (<60 ms). Type 2 EJPs consisted of two components: a small depolarization that was followed by a second depolarization with a faster rise time. In a third type of cell, at high strengths of stimulation, EJPs resembled type 1 EJPs but at lower strengths of stimulation were similar in time courseto type 2 EJPs. 3. All EJPs were abolished by tetrodotoxin (1 mu M) and reduced by omega-conotoxin (0.1 mu M), but were unaffected by hexamethonium (0.1 mM), suggesting that they result from the release of transmitter from post-ganglionic nerve fibres. All responses persisted inthe presence of atropine (1 mu M) but were abolished following the desensitization of P-2-purinoceptors with alpha,beta-methylene ATP (m-ATP; 10 mu M). 4. Spontaneous excitatory junction potentials (SEJPs) were also recorded fr om most cells SEJPs were similar in appearance to fast single-component EJPs; however, in general they had a briefer timecourse. SEJPs persisted in the presence of tetrodotoxin (1 mu M). 5. The electrical proper ties of urinary bladder smooth muscle were also examined. Voltage changes induced by point current injection into cells had fast rates of rise and decay (time constant, 5-20 ms). The inputresistance of cells ranged between 12 and 108 M Omega. When recordings were taken from cells near the point of current injection, resultantelectrotonic potentials could be detected in only a small proportion of cells. 6. The results are discussed in relation to the idea that transmural nerve stimulation in the guinea-pig urinary bladder causes the activation of at least two different membrane conductances. Cells appear to be electrically coupled with one another. However, it is likely that coupling exists within discrete bundles of the smooth muscle.

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Documento generato il 27/10/20 alle ore 09:57:45