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1. To characterize NKY-722, a novel hydrophilic dihydropyridine derivative, as a Ca2+ antagonist, we examined its effects on 45Ca2+ influx, intracellular free Ca2+ concentrations [( Ca2+]i), and release of noradrenaline and adrenaline in bovine cultured adrenal chromaffin cells. 2. NKY-722 had little effect on basal 45Ca2+ influx into the resting cells, but inhibited high K+ (35.9 mM)-evoked 45Ca2+ influx in a concentration-dependent manner with an IC50 value of 5.2 nM. 3. NKY-722 inhibited high K(+)-evoked increases in [Ca2+]i in a concentration-dependent manner without effect on the resting [Ca2+]i. 4. NKY-722 had little effect on basal release of noradrenaline and adrenaline but inhibited high K(+)-evoked release of noradrenaline and adrenaline in a concentration-dependent manner with IC50 values of 5.0 nM and 4.8 nM, respectively. 5. Nicardipine, a prototype of NKY-722, also inhibited high K(+)-evoked 45Ca2+ influx and release of noradrenaline and adrenaline in a concentration-dependent manner: the IC50 value for high K(+)-evoked 45Ca2+ influx was 51 nM, and the values for high K(+)-evoked release of noradrenaline and adrenaline were 52 nM and 50 nM, respectively. 6. These results show that NKY-722 is a hydrophilic Ca2+ antagonist ten times more potent than nicardipine.
T Ohue, and
K Lee, and
K Koshimura, and
S Miwa
February 1993,
European journal of pharmacology,
T Ohue, and
K Lee, and
K Koshimura, and
S Miwa
March 1989,
Cardiovascular drugs and therapy,
T Ohue, and
K Lee, and
K Koshimura, and
S Miwa
April 1991,
European journal of pharmacology,
T Ohue, and
K Lee, and
K Koshimura, and
S Miwa
May 1998,
Neuroscience letters,
T Ohue, and
K Lee, and
K Koshimura, and
S Miwa
January 1995,
British journal of pharmacology,
T Ohue, and
K Lee, and
K Koshimura, and
S Miwa
November 1993,
The European journal of neuroscience,
T Ohue, and
K Lee, and
K Koshimura, and
S Miwa
October 1985,
The Journal of physiology,
T Ohue, and
K Lee, and
K Koshimura, and
S Miwa
January 1987,
Journal of neurochemistry,
T Ohue, and
K Lee, and
K Koshimura, and
S Miwa
May 1996,
Neuron,
T Ohue, and
K Lee, and
K Koshimura, and
S Miwa
December 2001,
Naunyn-Schmiedeberg's archives of pharmacology,
