Related Experiment Video
Updated: Jul 29, 2026

In vitro Measurements of Tracheal Constriction Using Mice
Published on: June 25, 2012
Carbachol and nitric oxide inhibition of Na,K-ATPase activity in bovine ciliary processes
D Z Ellis1, J A Nathanson, J Rabe
1Neuroscience Center, Massachusetts General Hospital, Charlestown, MA 02129, USA. ellis@helix.mgh.harvard.edu
Purpose:
Nitric oxide (NO) donors and cholinergic agents decrease intraocular pressure, in part because they induce a decrease in aqueous humor production. Because Na,K-adenosine triphosphatase (ATPase) is involved in aqueous humor formation, this study was conducted to investigate the hypothesis that NO and cholinomimetics regulate its activity in bovine ciliary processes.
Methods:
Bovine tissue slices were incubated with agonists and antagonists in a physiological buffer in vitro. Na,K-ATPase activity was determined by assaying hydrolysis of adenosine triphosphate (ATP) in suspended permeabilized tissue slices.
Results:
Carbachol-induced inhibition of Na,K-ATPase activity correlated with increases in cGMP. This inhibition was abolished by the muscarinic blocker atropine, the NO inhibitor N(w)-nitro-L-arginine (L-NAME) and the soluble guanylate cyclase inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ). Sodium nitroprusside (SNP) mimicked the actions of carbachol. The SNP-induced decrease in Na,K-ATPase activity correlated with an increase in cGMP and was also abolished by ODQ. Both 8-bromo (Br)-cGMP and okadaic acid also inhibited Na,K-ATPase activity.
Conclusions:
Carbachol-induced inhibition of Na,K-ATPase activity involves muscarinic receptor activation. That SNP mimics and L-NAME reverses carbachol's effect on Na,K-ATPase activity suggests that the actions of carbachol are mediated by NO. Carbachol's and SNP's effects on Na,K-ATPase activity involved soluble guanylate cyclase and cGMP. Inhibition of Na,K-ATPase activity by 8-Br-cGMP and okadaic acid indicates that protein phosphorylation events may mediate SNP-induced inhibition of Na,K-ATPase activity.
More Related Videos
10:46Mechanical Stimulation-induced Calcium Wave Propagation in Cell Monolayers: The Example of Bovine Corneal Endothelial Cells
Published on: July 16, 2013
07:32Isolating and Using Sections of Bovine Mesenteric Artery and Vein as a Bioassay to Test for Vasoactivity in the Small Intestine
Published on: October 7, 2014
Related Concept Videos
Nitric Oxide Signaling Pathway
Direct-Acting Cholinergic Agonists: Chemistry and Structure-Activity Relationship
The direct-acting...
Direct-Acting Cholinergic Agonists: Pharmacokinetics
Direct-Acting Cholinergic Agonists: Therapeutic Uses
Indirect-Acting Cholinergic Agonists: Mechanism of Action
Reversible inhibitors like edrophonium bind to a specific part of the enzyme called the anionic catalytic site. They form noncovalent bonds, which means they are not strongly attached to the enzyme. This creates a temporary and less stable enzyme–inhibitor complex, leading to...
Adrenergic Receptors: β Subtype
Isoprenaline > Adrenaline > Noradrenaline
Neurotransmitter binding to these receptors causes activation of adenylyl cyclase resulting in increased concentrations of cAMP and modulation of calcium ion channels within the cell. They are further classified into β1, β2, and β3 subtypes.
β1-adrenoceptors: β1-adrenoceptors have equal affinities for...