Article

omega-Agatoxin IVA blocks nicotinic receptor channels in bovine chromaffin cells.

Departamento de Farmacología, Universidad de Alicante, Spain.
FEBS Letters (impact factor: 3.54). 04/1995; 362(1):15-8. pp.15-8
Source: PubMed

ABSTRACT We have studied the contribution of P-type voltage-dependent Ca2+ channels to both catacholamine (CA) and ATP secretion from bovine chromaffin cells induced by high K+ or nicotine using omega-agatoxin IVA, a selective blocker of P-type voltage-dependent Ca2+ channels. We found that high K+ (75 mM) induced the release of about 13% of norepinephrine, 5% epinephrine and 11% ATP, and that omega-agatoxin (100 nM) did not affect this secretion. However, both nicotine-induced CA and ATP secretion were significantly blocked (about 50%) by omega-agatoxin IVA (100 nM). In addition, this toxin also reversibly blocked (about 70%) the inward current induced by nicotine in bovine chromaffin cells. The results suggest that, besides its known action of blocking P-type voltage-dependent channels, omega-agatoxin is a potent and reversible blocker of the nicotinic receptor channel in chromaffin cells, and that this action would explain the blockade of nicotine-induced secretion.

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Keywords

5% epinephrine
 
bovine chromaffin cells
 
bovine chromaffin cells induced
 
catacholamine
 
chromaffin cells
 
inward current induced
 
known action
 
nicotine-induced
 
nicotine-induced secretion
 
nicotinic receptor channel
 
norepinephrine
 
omega-agatoxin
 
omega-agatoxin IVA
 
P-type voltage-dependent Ca2+ channels
 
P-type voltage-dependent channels
 
reversible blocker
 
selective blocker
 
toxin