Differential effects of voltage dependent Ca2+ channels on low and high frequency mediated neurotransmission in guinea-pig ileum and rat vas deferens

1997 ◽  
Vol 335 (1) ◽  
pp. 31-36 ◽  
Author(s):  
Sandy Tran ◽  
John R Boot
Keyword(s):  
Guinea Pig ◽  
High Frequency ◽  
Vas Deferens ◽  
Rat Vas Deferens ◽  
Guinea Pig Ileum ◽  
Differential Effects ◽  
Voltage Dependent ◽  
Ca2 Channels

Ca(2+)-induced inhibition of 45Ca2+ influx and Ca2+ current in smooth muscle of the rat vas deferens

1996 ◽  
Vol 270 (5) ◽  
pp. C1468-C1477 ◽  
Author(s):  
M. A. Khoyi ◽  
T. Ishikawa ◽  
K. D. Keef ◽  
D. P. Westfall
Keyword(s):  
Vas Deferens ◽  
Rat Vas Deferens ◽  
Inhibitory Effects ◽  
Isolated Cells ◽  
Inositol 1,4,5 Trisphosphate ◽  
Voltage Dependent ◽  
Steady State Inactivation ◽  
Inward Currents ◽  
K Concentration ◽  
Ca2 Channels

The present study investigates how changes in intracellular Ca2+ concentration modulate the influx of 45Ca2+ in isolated rat vasa deferentia. Raising extracellular K+ concentration ([K+]0) to > or = 32 mM increased 45Ca2+ influx during the 1st min in solutions containing 0.03-1.5 mM extracellular Ca2+ concentration ([Ca2+]0). During the 6th min in [K+]0 > or = 50 mM, 45Ca2+ influx was less than during the 1st min. This decline in 45Ca2+ influx occurred for [Ca2+]0 > or = 0.4 mM. Procaine potentiated K(+)-stimulated 45Ca2+ influx in 1.5 mM [Ca2+]0 and eliminated the decline of 45Ca2+ influx in low [Ca2-]0. Ryanodine and norepinephrine reduced K(+)-stimulated 45Ca2+ influx. 45Ca2+ content changed with time in accordance with the changes observed in 45Ca2+ influx. In isolated cells, voltage-dependent inward currents inactivated more rapidly with 1.5 mM Ca2+ as the charge carrier than with 1.5 mM Ba2+, and the steady-state inactivation relationship was shifted in the hyperpolarizing direction. Inward current was reduced with either caffeine, ryanodine, or norepinephrine. The inhibitory effects of norepinephrine were abolished by depletion of intracellular Ca2+ stores. These results are compatible with the hypothesis that K(+)-stimulated 45Ca2+ influx declines with time due to Ca(2+)-induced inhibition of Ca2- channels. Ca(2+)- and inositol 1,4,5-trisphosphate-induced releases of Ca2+ from the sarcoplasmic reticulum appear to play an important role in this process.

Opiatelike actions of eseroline, an eserine derivative

1981 ◽  
Vol 59 (3) ◽  
pp. 307-310 ◽  
Author(s):  
K. Jhamandas ◽  
J. Elliott ◽  
M. Sutak
Keyword(s):  
Guinea Pig ◽  
Myenteric Plexus ◽  
Vas Deferens ◽  
Longitudinal Muscle ◽  
Rat Vas Deferens ◽  
Anticholinesterase Activity ◽  
Muscle Preparation ◽  
Guinea Pig Ileum ◽  
Anesthetized Rats ◽  
Release Of Acetylcholine

Eseroline, an eserine derivative without anticholinesterase activity, was tested in several systems for opiatelike activity. Eseroline depressed the twitch of the field-stimulated guinea pig ileum myenteric plexus longitudinal muscle preparation but failed to depress the twitch of the rat vas deferens. Intraperitoneal injections of eseroline in rats induced naloxone-antagonizable analgesia and catalepsy. Eseroline failed to influence the release of acetylcholine from the cortex of anesthetized rats. These observations have implications for studies in which eserine is used as a pharmacological tool.

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