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cGMP Accumulation (cgmp + accumulation)
Selected AbstractsInhibition of calcium-calmodulin kinase restores nitric oxide production and signaling in submandibular glands of a mouse model of salivary dysfunctionBRITISH JOURNAL OF PHARMACOLOGY, Issue 8 2004Florencia Rosignoli Nitric oxide is an intracellular and diffusible messenger of neurotransmitters involved in salivary secretion, as well as an inflammatory mediator in salivary gland diseases. It is synthesized by three different isoforms of nitric oxide synthase (NOS), each subject to a fine transcriptional, post-transcriptional and/or post-translational regulation. Our purpose was to study the possible mechanisms leading to NOS downregulation in submandibular glands of normal mice and in the nonobese diabetic (NOD) mouse model of salivary dysfunction with lower NOS activity. NOS activity and cGMP accumulation were determined by radioassays in submandibular glands of both mice in the presence of the protein kinase inhibitors KN-93 and bisindolylmaleimide. NOS I mRNA and protein expression and localization were assessed by RT,PCR, Western blot and immunohistochemistry. A downregulatory effect of calcium,calmodulin kinase II (CaMK II) on NOS activity in submandibular glands of both NOD and BALB/c mice was observed. Our results are consistent with a physiological regulation of NOS activity by this kinase but not by PKC in normal BALB/c mice. They are also supportive of a role for CaMK II in the lack of detectable NOS activity in submandibular glands of NOD mice. KN-93 also restored cGMP accumulation in NOD submandibular glands. The downregulation of NOS in NOD mice seems to be mainly mediated by this kinase rather than the result of a lower expression or different cellular localization of the enzyme. It was not related to different substrate or cofactors availability either. British Journal of Pharmacology (2004) 143, 1058,1065. doi:10.1038/sj.bjp.0705952 [source] Activation and potentiation of the NO/cGMP pathway by NG -hydroxyl- L -arginine in rabbit corpus cavernosum under normoxic and hypoxic conditions and ageingBRITISH JOURNAL OF PHARMACOLOGY, Issue 1 2003Javier Angulo When nitric oxide synthase (NOS) produces NO from NG -hydroxy- L -arginine (OH-arginine) instead of L -arginine, the total requirement of molecular oxygen and NADPH to form NO is reduced. The aim of this work was to evaluate the effects of OH-arginine on the contractility of rabbit corpus cavernosum (RCC) and to compare the capacities of L -arginine and OH-arginine to enhance NO-mediated responses under normoxic and hypoxic conditions and in ageing, as models of defective NO production. OH-arginine, but not L -arginine, was able to relax phenylephrine-contracted rabbit trabecular smooth muscle. OH-arginine-induced relaxation was inhibited by the NOS-inhibitor, L -NNA (300 ,M), and by the guanylyl cyclase inhibitor, ODQ (20 ,M), while it was not affected by the cytochrome P450 oxygenase inhibitor, miconazole (0.1 mM). Administration of OH-arginine, but not L -arginine, produced a significant increment of cGMP accumulation in RCC tissue. Relaxation elicited by OH-arginine (300 ,M) was still observed at low oxygen tension. The increase of cGMP levels induced by ACh (30 ,M) in RCC was significantly enhanced by addition of OH-arginine (300 ,M) in normoxic conditions, as well as under hypoxia, while L -arginine did not alter the effects of ACh on cGMP accumulation. Endothelium-dependent and nitrergic nerve-mediated relaxations were both significantly reduced in RCC from aged animals (>20-months-old) when compared with young adult rabbits (5-months-old). Treatment with OH-arginine (300 ,M) significantly potentiated endothelium-dependent and neurogenic relaxation in corpus cavernosum from aged rabbits, while L -arginine (300 ,M) did not have significant effects. Results show that OH-arginine promotes NO-mediated relaxation of RCC and potentiates the NO-mediated responses induced by stimulation of endogenous NO generation in hypoxic and aged tissues. We propose that the use of OH-arginine could be of interest in the treatment of erectile dysfunction, at least in those secondary to defective NO production. British Journal of Pharmacology (2003) 138, 63,70. doi:10.1038/sj.bjp.0705027 [source] The Presence of B-type Natriuretic Peptide in Burns and the Responsiveness of Fibroblasts to BNP: Proof of PrincipleACADEMIC EMERGENCY MEDICINE, Issue 6 2007Adam J. Singer MD Background:B-type natriuretic peptide (BNP) released from cardiac myocytes plays an important role in cardiac homeostasis through cyclic guanosine monophosphate (cGMP) activation. BNP also reduces cardiac remodeling and fibrosis. The antifibrotic effects of BNP are mediated in part by blocking the effects of transforming growth factor ,, a profibrotic cytokine that plays a significant role in cutaneous wound healing. It is unclear if BNP plays any role in cutaneous wound healing.ObjectivesTo investigate if BNP levels would be elevated in thermally injured human skin and if human-derived fibroblasts would respond to BNP exposure by increasing levels of cGMP.MethodsThis was an in vitro analysis of human skin. Skin samples and cells were collected from patients with and without thermal injury. The authors stained three skin samples from normal skin (taken at the time of elective cosmetic surgery) with antibodies to BNP and compared these with three tissue samples obtained from burned human skin taken during tangential excision of deep burns. Normal human-derived fibroblasts and keratinocytes were exposed in triplicate to BNP in vitro, and cGMP accumulation was evaluated. Levels of cGMP were quantified and compared with analysis of variance.ResultsBNP was present in all specimens of thermally injured skin (especially around collagen, epithelial cells, and endothelial cells) but not in any uninjured skin samples (p = 0.05, single-tailed Fisher's exact test). In vitro grown fibroblasts showed significant increases of cGMP levels with increasing levels of BNP exposure (mean [±SD]: 0.6 [±0.3], 1.2 [±0.2], 4.6 [±0.1], and 5.0 [±0.9] pmol/mL with BNP concentrations of 0, 10, 500, and 1,000 nmol/L, respectively; p < 0.001). The effect of BNP on keratinocytes was minimal and below the level of quantification.Conclusions:These findings demonstrate proof of principle that human fibroblasts are responsive to the effects of BNP in vitro and that BNP is present in injured skin, suggesting that BNP may play a role in cutaneous wound healing. [source] Nitric Oxide-Sensitive Guanylyl Cyclase Activity Inhibition Through Cyclic GMP-Dependent DephosphorylationJOURNAL OF NEUROCHEMISTRY, Issue 5 2000Rut Ferrero Abstract: The soluble form of guanylyl cyclase (sGC) plays a pivotal role in the transduction of inter- and intracellular signals conveyed by nitric oxide. Here, a feedback inhibitory mechanism triggered by cyclic guanosine-3,,5,-monophosphate (cGMP)-dependent protein kinase (PKG) activation is described. Preincubation of chromaffin cells with C-type natriuretic peptide, which increased cGMP levels and activated PKG, or with cGMP-permeant analogue (which also activates PKG), in the presence of a broad-spectrum phosphodiesterase inhibitor, resulted in a decrease in subsequent sodium nitroprusside (SNP)-dependent cGMP elevations. This inhibitory effect was mimicked by activating a protein phosphatase and counteracted by the selective PKG inhibitor KT-5823 and by different protein phosphatase inhibitors. Immunoprecipitation of sGC from cells submitted to different treatments followed by immunodetection with antiphosphoserine antibodies (clone 4A9) showed changes in phosphorylation levels of the , subunit of sGC, and these changes correlated well with differences in SNP-elicited cGMP accumulations. Pretreatment of cells with several PKG inhibitors or protein phosphatase inhibitors produced an enhancement of SNP-stimulated cGMP rises without changing the SNP concentration required to produce half-maximal or maximal responses. Taken together, these results indicate that the catalytic activity of sGC is closely coupled to the phosphorylation state of its , subunit and that the tonic activity of PKG or its stimulation regulates sGC activity through dephosphorylation of the , subunit. [source] | ||||||||||