ISSN:
1432-1424
Keywords:
nerve growth factor
;
dorsal root ganglia
;
sodium channels
;
patch clamp
;
channel development
;
tetrodotoxin
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
Summary The influence of nerve growth factor (NGF) on Na currents of rat dorsal root ganglia (DRG) was studied in neurons obtained from newborns and cultured for 2–30 hr inserum-free defined medium (SFM). Cell survival for the period studied was 78–87% both with and without NGF. Na currents were detected in all cells cultured for 6–9 hr. They were also detected after 2 hr in culture in 21.5% of the cells cultured without NGF (−NGF cells), and in 91.5% of the cells cultured with NGF (+NGF cells). Current density of the -NGF cells was 2.3 and 2 pA/μm2 after growth for 2 and 6–9 hr, respectively, compared to 3.0 and 3.9 pA/μm2 for the +NGF cells. The +NGF cells were separated into fast (F), Intermediate (I) and slow (S) cells, based on the Na current they expressed, while -NGF cells were all of theI type.F, I andS currents differed in their voltage-dependent inactivation (Vh 50=−79, −28 and −20 mV), kinetics of inactivation (tau h =0.55, 1.3 and 7.75 msec), and TTX sensitivity (K i=60, 550 and 1100nm). All currents were depressed by [Ca] o with aKd Ca of 22, 17 and 8mm forF, I andS currents, respectively. Current density ofF andS currents was 5.5 and 5 pA/μm2 for theI current. The concentration-dependent curve ofI currentvs. TTX indicated thatI current has two sites: one withF-like and another withS-likeK i for TTX. Hybridization ofF andS currents yieldI-like currents. Thus, the major effect of NGF on Na currents in SFM is the accleration of Na current acquisition and diversity, reflected in an increase of either theS orF type in a cell.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01869102
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