Search results for "Calcium Channel Agonists"

Cardiovascular effects induced by rolipram, a selective cAMP phosphodiesterase inhibitor: Interaction with adrenergic and calcium affecting drugs

1990

The phototransduction cascade in the isolated chick pineal gland revisited.

2003

It is well established that the isolated chick pineal gland is directly light sensitive and that melatonin synthesis of the gland can be inhibited by exposing the gland to light during scotophase. Since not all the steps of the phototransduction cascade have been clarified to the same extent as in the retina, we have treated isolated chick pineal glands with 90 min of light during scotophase and with drugs that affect key-components of vertebrate phototransduction, i.e., cyclic guanosine monophosphate (cGMP) phosphodiesterase 6 (PDE6), cGMP levels and cGMP-gated calcium channels. The endpoint measured was the activity of the rate-limiting enzyme of melatonin synthesis, arylalkylamine N-acet…

Mode and mechanism of neurotensin action in rat proximal colon

1997

Abstract This study examined the mechanism of action of neurotensin on intraluminal pressure in rat proximal colon. The direct and indirect contractile response to neurotensin (100 nM) was abolished in Ca 2+ -free solution, and was antagonized by nifedipine (1–5–10 nM) and potentiated by Bay K 8644 (methyl 1,4-dihydro-2,6-dimethyl-3-nitro-4-(2-trifluoromethylphenyl)-pyridine-5-carboxylate) (10–100–1000 nM). Neurotensin, in the presence of nifedipine (10 nM) and atropine (1 μM), induced a tetrodotoxin-insensitive inhibitory effect, which was antagonized by SR 48692 (2[(1-(7-chloro-4-quinolinyl)-5-(2,6-dimethoxy-phenyl)pyrazol-3-yl) carbonyl amino]tricyclo (3.3.1.1. 3.7 ) decan-2-carboxylic a…

Effect of different treatments in calcium-free medium on basal tone and contractile responses of guinea pig tracheae.

1995

Acetylcholine (ACh; 0.1 mmol/l) and KCl (80 mmol/l) induce a biphasic contractile response in isolated guinea pig tracheae maintained at 37 degrees C either in the presence or absence of extracellular Ca2+. Exposure of the tissue to Ca(2+)-free solution evokes a significant decrease in basal tone and the sources of Ca2+ appear to be decreased by prolonged agonist stimulation, and even more by successive agonist stimulation. After an incubation period of 20 min in Ca(2+)-containing solution, the response is restored. Mg(2+)-depletion in Ca(2+)-free medium increased the contractile response to ACh, but not to KCl, and delayed the tonic component of the next contraction elicited in Ca(2+)-cont…