ISSN:
1432-2013
Keywords:
Frog
;
Skeletal muscle
;
Chloride conductance
;
Potassium conductance
;
Protein kinase C
;
Protein kinase A
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract The membrane electrical properties and resting ionic conductances of frog semitendinosus muscle fibres were studied in vitro at 25° C with the two-microelectrode cable technique, in the presence of an activator or inhibitor of protein kinase C (PKC) or in the presence of an activator of adenylate cyclase. The PKC activator, 4β-phorbol 12,13-dibutyrate (4β-PDB), reduced chloride conductance (G Cl) at concentrations greater than 1 μM and did not affect potassium conductance (G K). At 150 μM, the maximum concentration of 4β-PDB tested, G Cl was reduced by 42%. The “inactive” phorbol ester 4α-phorbol 12,13-dibutyrate did not affect G Cl or G K. The inhibitory effect of 4β-PDB on G Cl was prevented by pretreatment of the muscle preparation with the PKC inhibitor staurosporine. The adenylate cyclase activator forskolin (1.5–8 μM) significantly increased the G K of the fibres, without affecting G Cl. Thus, we conclude that frog skeletal muscle G Cl, unlike rat muscle G Cl, is relatively insensitive to activators of PKC. Moreover, in frog muscle, protein kinase A is a likely modulator of G K, but not G Cl.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00374393
Permalink
