Human Trabecular Meshwork Cell Volume Decrease by NO-Independent Soluble Guanylate Cyclase Activators YC-1 and BAY-58-2667 Involves the BKCaIon Channel

2009 ◽  
Vol 50 (7) ◽  
pp. 3353 ◽  
Author(s):  
William M. Dismuke ◽  
Najam A. Sharif ◽  
Dorette Z. Ellis
Keyword(s):  
Cell Volume ◽  
Guanylate Cyclase ◽  
Trabecular Meshwork ◽  
Soluble Guanylate Cyclase ◽  
Trabecular Meshwork Cell ◽  
Volume Decrease

scholarly journals Human trabecular meshwork cell volume regulation

2002 ◽  
Vol 283 (1) ◽  
pp. C315-C326 ◽  
Author(s):  
Claire H. Mitchell ◽  
Johannes C. Fleischhauer ◽  
W. Daniel Stamer ◽  
K. Peterson-Yantorno ◽  
Mortimer M. Civan
Keyword(s):  
Cell Volume ◽  
Trabecular Meshwork ◽  
Regulatory Volume Decrease ◽  
Cell Volume Regulation ◽  
Channel Blockers ◽  
Uptake Mechanism ◽  
Fluid Uptake ◽  
Intracellular Ca ◽  
Predominant Effect ◽  
Volume Decrease

The volume of certain subpopulations of trabecular meshwork (TM) cells may modify outflow resistance of aqueous humor, thereby altering intraocular pressure. This study examines the contribution that Na+/H+, Cl−/HCO[Formula: see text]exchange, and K+-Cl− efflux mechanisms have on the volume of TM cells. Volume, Cl− currents, and intracellular Ca2+ activity of cultured human TM cells were studied with calcein fluorescence, whole cell patch clamping, and fura 2 fluorescence, respectively. At physiological bicarbonate concentration, the selective Na+/H+ antiport inhibitor dimethylamiloride reduced isotonic cell volume. Hypotonicity triggered a regulatory volume decrease (RVD), which could be inhibited by the Cl− channel blocker 5-nitro-2-(3-phenylpropylamino)-benzoate (NPPB), the K+channel blockers Ba2+ and tetraethylammonium, and the K+-Cl− symport blocker [(dihydroindenyl)oxy]alkanoic acid. The fluid uptake mechanism in isotonic conditions was dependent on bicarbonate; at physiological levels, the Na+/H+ exchange inhibitor dimethylamiloride reduced cell volume, whereas at low levels the Na+-K+-2Cl− symport inhibitor bumetanide had the predominant effect. Patch-clamp measurements showed that hypotonicity activated an outwardly rectifying, NPPB-sensitive Cl− channel displaying the permeability ranking Cl− > methylsulfonate > aspartate. 2,3-Butanedione 2-monoxime antagonized actomyosin activity and both increased baseline [Ca2+] and abolished swelling-activated increase in [Ca2+], but it did not affect RVD. Results indicate that human TM cells display a Ca2+-independent RVD and that volume is regulated by swelling-activated K+ and Cl− channels, Na+/H+ antiports, and possibly K+-Cl− symports in addition to Na+-K+-2Cl− symports.

NO-induced regulation of human trabecular meshwork cell volume and aqueous humor outflow facility involve the BKCa ion channel

2008 ◽  
Vol 294 (6) ◽  
pp. C1378-C1386 ◽  
Author(s):  
William M. Dismuke ◽  
Chigozirim C. Mbadugha ◽  
Dorette Z. Ellis
Keyword(s):  
Cell Volume ◽  
Trabecular Meshwork ◽  
Time Course ◽  
Soluble Guanylate Cyclase ◽  
Anterior Segment ◽  
Drug Application ◽  
Cellular Mechanisms ◽  
No Donors ◽  
Outflow Facility ◽  
Aqueous Humor Outflow

Nitric oxide (NO) donors decrease intraocular pressure (IOP) by increasing aqueous outflow facility in the trabecular meshwork (TM) and/or Schlemm's canal. However, the cellular mechanisms are unknown. Cellular mechanisms known to regulate outflow facility include changes in cell volume and cellular contractility. In this study, we investigated the effects of NO donors on outflow facility and NO-induced effects on TM cell volume. We tested the involvement of soluble guanylate cyclase (sGC), cGMP, PKG, and the large-conductance Ca2+-activated K+ (BKCa) channel using inhibitors and activators. Cell volume was measured using calcein AM fluorescent dye, detected by confocal microscopy, and quantified using NIH ImageJ software. An anterior segment organ perfusion system measured outflow facility. NO increased outflow facility in porcine eye anterior segments (0.4884–1.3956 μl·min−1·mmHg−1) over baseline (0.2373–0.5220 μl·min−1·mmHg−1) within 10 min of drug application. These NO-induced increases in outflow facility were inhibited by the the BKCa channel inhibitor IBTX. Exposure of TM cells to NO resulted in a 10% decrease in cell volume, and these decreases were abolished by the sGC inhibitor 1 H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one and IBTX, suggesting the involvement of sGC and K+ eflux, respectively. NO-induced decreases in cell volume were mimicked by 8-Br-cGMP and abolished by the PKG inhibitor (RP)-8-Br-PET-cGMP-S, suggesting the involvement cGMP and PKG. Additionally, the time course for NO-induced decreases in TM cell volume correlated with NO-induced increases in outflow facility, suggesting that the NO-induced alterations in cell volume may influence outflow facility.

Soluble Guanylate Cyclase Stimulators and Activators: Where are We and Where to Go?

2019 ◽  
Vol 19 (18) ◽  
pp. 1544-1557 ◽  
Author(s):  
Sijia Xiao ◽  
Qianbin Li ◽  
Liqing Hu ◽  
Zutao Yu ◽  
Jie Yang ◽  
...  
Keyword(s):  
Guanylate Cyclase ◽  
Soluble Guanylate Cyclase ◽  
Muscle Relaxation ◽  
Cyclic Guanosine Monophosphate ◽  
Guanosine Monophosphate ◽  
Smooth Muscle Relaxation ◽  
Secondary Messenger ◽  
Physiological Processes ◽  
Cgmp Pathway ◽  
Preclinical And Clinical Studies

Soluble Guanylate Cyclase (sGC) is the intracellular receptor of Nitric Oxide (NO). The activation of sGC results in the conversion of Guanosine Triphosphate (GTP) to the secondary messenger cyclic Guanosine Monophosphate (cGMP). cGMP modulates a series of downstream cascades through activating a variety of effectors, such as Phosphodiesterase (PDE), Protein Kinase G (PKG) and Cyclic Nucleotide-Gated Ion Channels (CNG). NO-sGC-cGMP pathway plays significant roles in various physiological processes, including platelet aggregation, smooth muscle relaxation and neurotransmitter delivery. With the approval of an sGC stimulator Riociguat for the treatment of Pulmonary Arterial Hypertension (PAH), the enthusiasm in the discovery of sGC modulators continues for broad clinical applications. Notably, through activating the NO-sGC-cGMP pathway, sGC stimulator and activator potentiate for the treatment of various diseases, such as PAH, Heart Failure (HF), Diabetic Nephropathy (DN), Systemic Sclerosis (SS), fibrosis as well as other diseases including Sickle Cell Disease (SCD) and Central Nervous System (CNS) disease. Here, we review the preclinical and clinical studies of sGC stimulator and activator in recent years and prospect for the development of sGC modulators in the near future.

scholarly journals Discovery of the Soluble Guanylate Cyclase Activator Runcaciguat (BAY 1101042)

2021 ◽  
Author(s):  
Michael G. Hahn ◽  
Thomas Lampe ◽  
Sherif El Sheikh ◽  
Nils Griebenow ◽  
Elisabeth Woltering ◽  
...  
Keyword(s):  
Guanylate Cyclase ◽  
Soluble Guanylate Cyclase ◽  
Guanylate Cyclase Activator ◽  
Cyclase Activator

Circumferential trabecular meshwork cell density in the human eye

2021 ◽  
Vol 205 ◽  
pp. 108494
Author(s):  
Markus H. Kuehn ◽  
Janice A. Vranka ◽  
David Wadkins ◽  
Thomas Jackson ◽  
Lin Cheng ◽  
...  
Keyword(s):  
Cell Density ◽  
Trabecular Meshwork ◽  
Human Eye ◽  
Trabecular Meshwork Cell
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