scholarly journals Potassium channel blockers and the effects of cromakalim on the smooth muscle of the guinea-pig bladder

1990 ◽  
Vol 99 (4) ◽  
pp. 779-785 ◽  
Author(s):  
K. Fujii ◽  
C.D. Foster ◽  
A.F. Brading ◽  
A.B. Parekh
Keyword(s):  
Smooth Muscle ◽  
Guinea Pig ◽  
Potassium Channel ◽  
Channel Blockers ◽  
Potassium Channel Blockers

Inhibition of small conductance K+-channels attenuated melatonin-induced relaxation of serotonin-contracted rat gastric fundus

2000 ◽  
Vol 78 (10) ◽  
pp. 799-806 ◽  
Author(s):  
M Storr ◽  
V Schusdziarra ◽  
H -D Allescher
Keyword(s):  
Smooth Muscle ◽  
Potassium Channel ◽  
Guanylate Cyclase ◽  
Inhibitory Effect ◽  
Gastric Fundus ◽  
Channel Blockers ◽  
Basal Tone ◽  
Potassium Channel Blockers ◽  
Rat Gastric Fundus ◽  
Small Conductance

The aim of this study was to investigate the effects of melatonin on rat gastric fundus smooth muscle. Melatonin (10-4 to10-3 M) had no effect on the basal tone of gastric smooth muscle. After precontraction with carbachol (10-6 M) or serotonin (10-7 M), melatonin caused a concentration dependent inhibitory action. The half maximal effect on serotonin-induced contraction was found with 1.12 beta 0.86 beta 10-5 M of melatonin. Increasing concentrations of melatonin (10-5 to 10-3 M) resulted in a right shift of the serotonin concentration response curve (10-10 to10-5 M). This inhibitory effect of melatonin was partially blocked in the presence of apamin (10-10 to 10-7 M), a specific blocker of the small conductance calcium-dependent potassium channel, but not in the presence of other potassium channel blockers like charybdotoxin (10-8 M), glibenclamide (10-5 M), or tetraethylammonium (ODQ, 10-4 M). The inhibitory effect was not changed in the presence of the neuronal blocker tetrodotoxin (10-6 M), the selective P2-receptor antagonist pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid (3 × 10-5 M), the nitric-oxide synthase inhibitor N-nitro-L-arginine (3 × 10-4 M), or the guanylate cyclase inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]-quinoxalin-1-one (10-4 M), suggesting that neither the purinergic, nitrergic, nor guanylate cyclase pathways were involved. We further investigated inhibitory responses to electrical field stimulation (EFS) at different frequencies under non-adrenergic, non-cholinergic (NANC) conditions on a serotonin-induced contraction in the presence of melatonin (10-5 to 10-4 M). Melatonin significantly reduced these inhibitory NANC responses in higher (8-32 Hz), but not lower (05-4 Hz), frequencies (16 Hz without melatonin, 103 ± 6.3%; melatonin 10-5 M, 80.4 ± 7.5%; melatonin 10-4 M, 39.1 ± 17.1%). Melatonin had no effect on contractile responses induced by EFS under basal tone. These results demonstrate that the inhibitory effect of melatonin in rat gastric fundus smooth muscle is apamin sensitive, but is not affected by other potassium channel blockers. This suggests that melatonin may be another transmitter candidate for the apamin sensitive responses within the gastrointestinal tract.Key words: melatonin, smooth muscle, apamin, NANC-inhibition, gastric, potassium channels.

Effects of potassium channel blockers on the acetylcholine-induced currents in dissociated outer hair cells of guinea pig cochlea

1997 ◽  
Vol 236 (2) ◽  
pp. 79-82 ◽  
Author(s):  
Takehito Yamamoto ◽  
Seiji Kakehata ◽  
Takechiyo Yamada ◽  
Takehisa Saito ◽  
Hitoshi Saito ◽  
...  
Keyword(s):  
Guinea Pig ◽  
Potassium Channel ◽  
Hair Cells ◽  
Outer Hair Cells ◽  
Channel Blockers ◽  
Guinea Pig Cochlea ◽  
Potassium Channel Blockers ◽  
Induced Currents

scholarly journals Potassium channel blockers differentially affect carbachol and (−)-N6-phenylisopropyladenosine on guinea-pig atria

1989 ◽  
Vol 97 (3) ◽  
pp. 866-872 ◽  
Author(s):  
Mariella Biasi ◽  
Guglielmina Froldi ◽  
Eugenio Ragazzi ◽  
Luisa Pandolfo ◽  
Laura Caparrotta ◽  
...  
Keyword(s):  
Guinea Pig ◽  
Potassium Channel ◽  
Channel Blockers ◽  
Potassium Channel Blockers ◽  
Guinea Pig Atria

Proteinase inhibitor homologues as potassium channel blockers

1994 ◽  
Vol 1 (4) ◽  
pp. 246-250 ◽  
Author(s):  
Jean-Marc Lancelin ◽  
Marie-Françoise Foray ◽  
Marc Poncin ◽  
Michelle Hollecker ◽  
Dominique Marion
Keyword(s):  
Potassium Channel ◽  
Proteinase Inhibitor ◽  
Channel Blockers ◽  
Potassium Channel Blockers
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