Elevated intracellular levels of cyclic guanosine monophosphate (cGMP) may induce apoptosis, and at least some cancer cells seem to escape this effect by increased efflux of cGMP, as clinical studies have shown that extracellular cGMP levels are elevated in various types of cancer. The human ATP binding cassette (ABC) transporter ABCC5 transports cGMP out of cells, and inhibition of ABCC5 may h...

Intact rat peritoneal macrophages (rPM) treated with 3-isobutyl-1-methylxanthine (IBMX), an inhibitor of phosphodiesterases (PDEs), accumulated more cGMP than untreated cells. A PDE activity toward [(3)H]cGMP was detected in the soluble and particulate fractions of rPM. The hydrolysis of cGMP was Ca(2+)/calmodulin-independent but increased in the presence of cGMP excess. Similar results were ob...

PURPOSE To evaluate the effect of 8-bromo cGMP (Br cGMP) on aqueous humor flow rate and outflow facility in monkey eyes. METHODS. Aqueous humor flow rate was measured fluorophotometrically after topical, intracameral, or intravitreal administration of Br cGMP in one eye and normal saline in the other eye. Outflow facility was determined by two-level constant pressure perfusion after intracamera...

When retinal sections were isolated from dark-adapted bullfrogs and placed in normal ringer's solution, they contained 40.7 +/- 0.2 pmol cGMP/mg protein (mean +/- SEM, 30 samples). When isolated, dark-adapted retinal sections were removed from normal ringer's solution and placed in calcium-deficient ringer's solution with 3 mM EGTA, there was about a threefold rise in cyclic GMP (cGMP) levels b...

We tested the hypothesis that cardiac myocytes from hypertensive (one kidney, one clip; 1K,1C) cardiac-hypertrophied rabbits require higher guanosine 3',5'-cyclic monophosphate (cGMP) to similarly lower O2consumption than control myocytes and that this effect is caused by differences in guanylate cyclase activity. Using isolated myocytes from control and 1K,1C New Zealand White rabbits, we obta...

The angiotensin AT2 receptor modulates renal production of cyclic guanosine 3',5'-monophosphate (cGMP; J. Clin. Invest. 1996. 97:1978-1982). In the present study, we hypothesized that angiotensin II (Ang II) acts at the AT2 receptor to stimulate renal production of nitric oxide leading to the previously observed increase in cGMP. Using a microdialysis technique, we monitored changes in renal in...

Both cAMP and cGMP are critical intracellular second messengers regulating fundamental physiological processes in the myocardium, from acute contraction/relaxation to chronic gene expression, cell growth and apoptosis, and cardiac structural remodeling. cAMP is synthesized by adenylate cyclases on activation of G-protein–coupled receptors. cGMP is generated from the cytosolic purine nucleotide ...

We measured concentrations of guanosine 3',5'-monophosphate (cGMP) in plasma and urine of healthy subjects and patients with congestive heart failure, renal impairment, neoplastic disease, and hepatic cirrhosis. There was no correlation between cGMP concentrations in urine and in plasma. In all patients except those with renal impairment, urinary cGMP concentrations were significantly higher th...

Carbon monoxide (CO) is an activator of soluble guanylyl cyclase and is implicated as a neuronal messenger. CO production, nitric oxide synthase (NOS) activity, and guanosine 3',5'-monophosphate (cGMP) levels were quantitated in cerebellar granule cell cultures. Metabolic labeling experiments enabled the direct measurement of neuronal CO production in vitro. CO production is significant, and pe...