Calpain activation contributes to hyperglycemia-induced endothelial dysfunction and apoptosis. This study was designed to investigate the role of calpain inhibition in improving diabetic erectile dysfunction (ED) in mice. Thirty-eight-week-old male C57BL/6J mice were divided into three groups: (1) nondiabetic control group, (2) diabetic mice + vehicle group, and (3) diabetic mice + MDL28170 (an inhibitor of calpain) group. Type 1 diabetes was induced by intraperitoneal injection of streptozotocin at 60 mg kg^-1 body weight for 5 consecutive days. Thirteen weeks later, diabetic mice were treated with MDL28170 or vehicle for 4 weeks. The erectile function was assessed by electrical stimulation of the cavernous nerve. Penile tissues were collected for measurement of calpain activity and the endothelial nitric oxide synthase (eNOS)-nitric oxide (NO)-cyclic guanosine monophosphate (cGMP) pathway. Terminal deoxynucleotidyl transferase 2'-deoxyuridine 5'-triphosphate nick end labeling (TUNEL) staining was used to evaluate apoptosis. Caspase-3 expression and activity were also measured to determine apoptosis. Our results showed that erectile function was enhanced by MDL28170 treatment in diabetic mice compared with the vehicle diabetic group. No differences in calpain-1 and calpain-2 expressions were observed among the three groups. However, calpain activity was increased in the diabetic group and reduced by MDL28170. The eNOS-NO-cGMP pathway was upregulated by MDL28170 treatment in diabetic mice. Additionally, MDL28170 could attenuate apoptosis and increase the endothelium and smooth muscle levels in corpus cavernosum. Inhibition of calpain could improve erectile function, probably by upregulating the eNOS-NO-cGMP pathway and reducing apoptosis.
Animals ; Apoptosis/drug effects* ; Calpain/antagonists & inhibitors* ; Cyclic GMP/biosynthesis* ; Diabetes Complications/drug therapy* ; Diabetes Mellitus, Experimental/complications* ; Dipeptides/therapeutic use* ; Endothelium/metabolism* ; Enzyme Inhibitors/therapeutic use* ; Erectile Dysfunction/etiology* ; In Situ Nick-End Labeling ; Male ; Mice ; Mice, Inbred C57BL ; Muscle, Smooth/metabolism* ; Nitric Oxide Synthase Type III/biosynthesis* ; Penis/enzymology* ; Up-Regulation

OBJECTIVETo prepare rabbit monoclonal antibody (RabMab) against guanosine 3', 5'-cyclic monophosphate (cGMP) and to develop a competitive ELISA for the detection of cGMP.

METHODSNew Zealand white rabbits were immunized with synthesized cGMP-keyhole limpet hemoeyanin (cGMP-KLH) to prepared a RabMAb with monoclonal antibody technique of Epitomics. A competitive ELISA kit was produced with cGMP RabMAb. The specificity, the precision and the recoveries of the method were determined.

RESULTSThe RabMAb with high sensitivity towards cGMP were prepared with an antibody timer of 3.1 ng/mL and 50% inhibitive concentration (IC50) of 12.57 ng/mL. The cGMP RabMAb had 33% cross-reactivity to inosine 3', 5'-cyclic monophosphate (cIMP) and little or no cross-reactivity to other compounds. A competitive ELISA was developed for detection of cGMP. The range of detection was 0~120 ng/mL with a minimal limit of 1.95 ng/mL. The recovery of assay was 89%~103%. The inter-assay and intra-assay coefficient variations were below 11.68% and 13.85%, respectively.

CONCLUSIONThe RabMab against cGMP with high affinity and high specificity has been generated successfully, and a competitive ELISA for detection of cGMP has been developed with the prepared cGMP RabMAb.

Animals ; Antibodies, Monoclonal ; biosynthesis ; Antibody Specificity ; Cross Reactions ; Cyclic GMP ; immunology ; Enzyme-Linked Immunosorbent Assay ; Rabbits

OBJECTIVETo examine whether calcineurin/NFAT signaling pathway mediates endothelin-1 (ET-1)-induced proliferation of pulmonary artery smooth muscle cells (PASMCs) by regulating phosphodiesterase-5 (PDE5) and the effect of the selective calcineurin inhibitor cyclosporine A and PDE5 inhibitor sildenafil on ET-1-induced PASMC proliferation.

METHODSPASMCs were treated with ET-1 to stimulate their proliferation with or without prior treatment of the cells with CsA or sildenafil. Calcineurin activity in the cells was measured using a calcineurin activity assay kit, PDE5 expression examined using immunoblotting, and cGMP level detected using a cGMP direct immunoassay kit. PASMC proliferation following the treatments was determined using [(3)H]thymidine incorporation assay.

RESULTSET-1 caused a 2.05-fold increase in the cellular calcineurin activity, a 1.80-fold increase in PDE5 expression, and a 3.20-fold increase in the DNA synthesis rate, and reduced the cGMP level by 67%. Pretreatment of the cells with Cyclosporine blocked the effects of ET-1, and PDE5 inhibition by sildenafil pretreatment also abolished ET-1-induced reduction of cGMP level in the cells. Both Cyclosporine and sildenafil suppressed ET-1-stimulated PASMC proliferation.

CONCLUSIONActivation of calcineurin/NFAT signaling pathway mediates ET-1-induced PASMC proliferation by stimulating PDE5 expression, which further degrades cGMP. Both Cyclosporine and sildenafil can suppress ET-1-stimulated PASMC proliferation in vitro.

Animals ; Calcineurin ; metabolism ; Cell Proliferation ; drug effects ; Cells, Cultured ; Cyclic GMP ; metabolism ; Cyclic Nucleotide Phosphodiesterases, Type 5 ; metabolism ; Cyclosporine ; DNA ; biosynthesis ; Endothelin-1 ; pharmacology ; Muscle, Smooth, Vascular ; cytology ; Myocytes, Smooth Muscle ; cytology ; enzymology ; NFATC Transcription Factors ; metabolism ; Piperazines ; Pulmonary Artery ; cytology ; Purines ; Rats ; Rats, Sprague-Dawley ; Signal Transduction ; Sildenafil Citrate ; Sulfones

Cyclic diguanylate (c-di-GMP) is a ubiquitous second messenger present in a wide variety of bacteria, which is responsible for cell differentiation, biofilm formation, pathogenic factor generation, and so on. The level of c-di-GMP in bacteria is regulated by two opposing active domains, diguanylate cyclase (DGC) and phosphodiesterase (PDE), which are present in the same bifunctional protein, and in charge of the synthesis and the degradation of c-di-GMP, respectively. The target of c-di-GMP in the bacterial cell consists of PilZ domain and GEMM riboswitch, the only riboswitch that involved in signal transduction. This article gives an overview of c-di-GMP, focusing on its metabolic pathway, regulatory mechanism, biological function of c-di-GMP, and the synthesis of c-di-GMP analogues and their biological activity.
Bacteria ; metabolism ; Cyclic GMP ; analogs & derivatives ; biosynthesis ; metabolism ; Escherichia coli Proteins ; chemistry ; metabolism ; Phosphoric Diester Hydrolases ; chemistry ; metabolism ; Phosphorus-Oxygen Lyases ; chemistry ; metabolism ; Riboswitch ; Second Messenger Systems ; Signal Transduction

The purpose of this study was to identify the effect of sildenafil citrate on IL-1 beta induced nitric oxide (NO) synthesis and iNOS expression in human synovial sarcoma SW982 cells. IL-1 beta stimulated the cells to generate NO in both dose- and time-dependent manners. The IL-1 beta -induced NO synthesis was inhibited by guanylate cyclase (GC) inhibitor, LY83583. When the cells were treated with 8-bromo-cGMP, a hydrolyzable analog of cGMP, NO synthesis was increased upto 5-fold without IL-1 beta treatment suggesting that cGMP is an essential component for increasing the NO synthesis. Synoviocytes and chondrocytes contain strong cGMP phosphodiesterase (PDE) activity, which has biochemical features of PDE5. When SW982 cells were pretreated with sildenafil citrate (Viagra), a PDE5 specific inhibitor, sildenafil citrate significantly inhibited IL-1 beta -induced NO synthesis and iNOS expressions. From this result, we noticed that PDE5 activity is required for IL-1 beta -induced NO synthesis and iNOS expressions in human synovial sarcoma cells, and sildenafil citrate may be able to suppress an inflammatory reaction of synovium through inhibition of NO synthesis and iNOS expression by cytokines.
Anti-Inflammatory Agents/immunology/pharmacology ; Cell Line, Tumor ; Cyclic GMP/analogs & derivatives/immunology/metabolism ; Cyclic Nucleotide Phosphodiesterases, Type 2/antagonists & inhibitors/metabolism ; Humans ; Interleukin-1beta/*metabolism ; Male ; Nitric Oxide/*biosynthesis/genetics/immunology ; Nitric Oxide Synthase Type II/*biosynthesis/genetics/immunology ; Phosphodiesterase Inhibitors/immunology/*pharmacology ; Piperazines/immunology/*pharmacology ; Purines/immunology/pharmacology ; Signal Transduction/drug effects/genetics/immunology ; Sulfones/immunology/*pharmacology ; Synovial Membrane/enzymology/immunology

BACKGROUNDBradykinin (BK) acts mainly on two receptor subtypes: B(1) and B(2), and activation of B(2) receptor mediates the most well-known cardioprotective effects of angiotensin converting enzyme inhibitors (ACEi), however, the role that B(1) receptor plays in ACEi has not been fully defined. We examined the role of B(1) receptor in the inhibitory effect of ACE inhibitor captopril on rat cardiomyocyte hypertrophy and cardiac fibroblast proliferation induced by angiotensin II (Ang II) and explored its possible mechanism.

METHODSNeonatal cardiomyocytes and cardiac fibroblasts (CFs) were randomly treated with Ang II, captopril, B(2) receptor antagonist (HOE-140) and B(1) receptor antagonist (des-Arg(10), Leu(9)-kallidin) alone or in combination. Flow cytometry was used to evaluate cell cycle, size and protein content. Nitric oxide (NO) and intracellular cyclic guanosine monophosphate (cGMP) level were measured by colorimetry and radioimmunoassay.

RESULTSAfter the CFs and cardiomyocytes were incubated with 0.1 micromol/L Ang II for 48 hours, the percentage of CFs in the S stage, cardiomyocytes size and protein content significantly increased (both P < 0.01 vs control), and these increases were inhibited by 10 micromol/L captopril. However, NO and cGMP levels were significantly higher than that with Ang II alone (both P < 0.01). 1 micromol/L HOE-140 or 0.1 micromol/L des-Arg(10), Leu(9)-kallidin attenuated the effects of captopril, which was blunted further by blockade of both B(1) and B(2) receptors.

CONCLUSIONSActing via B(2) receptor, BK contributes to the antihypertrophic and antiproliferative effects of captopril on cardiomyocytes and CFs. In the absence of B(2) receptor, B(1) receptor may act a compensatory mechanism for the B(2) receptor and contribute to the inhibition of cardiomyocyte hypertrophy and CFs proliferation by captopril. NO and cGMP play an important role in the effect of B(1) receptor.

Angiotensin-Converting Enzyme Inhibitors ; pharmacology ; Animals ; Animals, Newborn ; Captopril ; pharmacology ; Cardiomegaly ; prevention & control ; Cell Proliferation ; drug effects ; Cell Size ; drug effects ; Cyclic GMP ; analysis ; DNA ; biosynthesis ; Fibroblasts ; drug effects ; physiology ; Myocytes, Cardiac ; drug effects ; pathology ; Nitric Oxide ; analysis ; Rats ; Rats, Sprague-Dawley ; Receptor, Bradykinin B1 ; physiology

BACKGROUNDNitric oxide (NO) is a biologically active molecule which has been reported to protect the heart against ischemia and reperfusion injury in different species. This study aimed to test the hypothesis that nitric oxide may induce the expression of heat shock protein 72 (HSP72) which may protect the heart against ischemia.

METHODSRabbits were given intravenous saline or S-nitroso-N-acetylpenicillamine (SNAP), a nitric oxide donor, or Zaprinast, an inhibitor of cyclic guanosine monophosphate (GMP)-phosphodiesterase, which may increase myocardial cyclic GMP content. Twenty-four hours later, the rabbits were either sampled to measure HSP72, or induced with a 30-minute coronary occlusion followed by a 120-minute reperfusion, and then the infarct size was measured. Meanwhile, chelerythrine (CHE, an inhibitor of protein kinase C) was given intravenously 5 minutes before SNAP injection and the effect on HSP72 expression and infarct size was determined.

RESULTSTwenty-four hours after pretreatment, immunoblotting showed HSP72 expression increased in the SNAP group compared with control groups, and this was blocked by CHE. Myocardial infarct size in the SNAP group was smaller than that of the control group ((32.4 +/- 5.8)% vs (51.1 +/- 4.7)%, P < 0.05). Pretreated with CHE abolished the infarct size-limiting effect of SNAP ((46.0 +/- 5.1)%). Pretreatment with Zaprinast neither induced HSP72 expression nor reduced infarct size ((55.4 +/- 5.4)%).

CONCLUSIONNO induced HSP72 expression and a delayed protection to the heart via the activities of protein kinase C by a cyclic GMP-independent pathway.

Animals ; Benzophenanthridines ; pharmacology ; Cyclic GMP ; metabolism ; HSP72 Heat-Shock Proteins ; biosynthesis ; Hemodynamics ; Male ; Myocardial Infarction ; metabolism ; physiopathology ; prevention & control ; Myocardial Ischemia ; metabolism ; physiopathology ; prevention & control ; Nitric Oxide ; metabolism ; Nitric Oxide Donors ; pharmacology ; Phosphodiesterase Inhibitors ; pharmacology ; Protein Kinase C ; metabolism ; Purinones ; pharmacology ; Rabbits ; S-Nitroso-N-Acetylpenicillamine ; pharmacology

Prostaglandin E2(PGE2), a major product of cyclooxygenase, has been implicated in modulating angiogenesis, vascular function, and inflammatory processes, but the underlying mechanism is not clearly elucidated. We here investigated the molecular mechanism by which PGE 2 regulates angiogenesis. Treatment of human umbilical vein endothelial cells (HUVEC) with PGE 2 increased angiogenesis. PGE 2 increased phosphorylation of Akt and endothelial nitric oxide synthase (eNOS), eNOS activity, and nitric oxide (NO) production by the activation of cAMP-dependent protein kinase (PKA) and phosphatidylinositol 3-kinase (PI3K). Dibutyryl cAMP (DB-cAMP) mimicked the role of PGE 2 in angiogenesis and the signaling pathway, suggesting that cAMP is a down-stream mediator of PGE 2. Furthermore, PGE 2 increased endothelial cell sprouting from normal murine aortic segments, but not from eNOS-deficient ones, on Matrigel. The angiogenic effects of PGE 2 were inhibited by the inhibitors of PKA, PI3K, eNOS, and soluble guanylate cyclase, but not by phospholipase C inhibitor. These results clearly show that PGE 2 increased angiogenesis by activating the NO/cGMP signaling pathway through PKA/PI3K/Akt-dependent increase in eNOS activity.
1-Phosphatidylinositol 3-Kinase/antagonists & inhibitors ; Animals ; Aorta ; Cell Movement/drug effects ; Cell Proliferation/drug effects ; Cyclic AMP/metabolism/pharmacology ; Cyclic GMP/biosynthesis/*metabolism ; Dinoprostone/*pharmacology ; Endothelial Cells/*drug effects/metabolism ; Enzyme Inhibitors/pharmacology ; Humans ; Mice ; Mice, Knockout ; Neovascularization, Physiologic/*drug effects ; Nitric Oxide/biosynthesis/*metabolism ; Nitric Oxide Synthase Type III/deficiency/metabolism ; Phosphorylation/drug effects ; Proto-Oncogene Proteins c-akt/metabolism ; Rats ; Rats, Sprague-Dawley ; Research Support, Non-U.S. Gov't ; Signal Transduction/*drug effects ; Umbilical Veins/cytology/*drug effects/metabolism

Animals ; Cyclic GMP ; metabolism ; Ischemic Preconditioning, Myocardial ; Myocytes, Cardiac ; metabolism ; Nitric Oxide ; biosynthesis ; Rats ; Rats, Sprague-Dawley

OBJECTIVETo observe the expression and effect of human calcitonin gene-related peptide (hCGRP) gene mediated by recombinant adeno-associated virus (rAAV) in primary cultured corporal cavernosum smooth muscle cells of the rat and explore the possibility of using CGRP gene for gene therapy in erectile dysfunction.

METHODSThe primary cultured corporal cavernosum smooth muscle cells of the rat were randomly divided into 4 groups and infected with recombinant virus VssHGCMV-hCGRP, VssHGCMV, VssC-MV-GFP and the untreated, respectively. CGRP-like immunoreactivity was measured by protein dot blot assay in the 24 h-culture medium, and intracellular cAMP and cGMP levels in the cultured cells were also determined using radioimmunoassay to ascertain bioactivity of transduced CGRP.

RESULTSThe exogenous gene was transferred into primary corporal cavernosum smooth muscle cells by VssHGCMV-hCGRP infection and efficiently expressed. Compared with the control group, intracellular cAMP level in the cell infected by VssHGCMV-hCGRP was significantly increased (48.7 +/- 1.1 nmol/L vs 7.8 +/- 1.4 nmol/L, P < 0.01), whereas cGMP level remained unchanged in two groups, and CGRP-like immunoreactivity was also detected in the culture medium infected by VssHGCMV- hCGRP.

CONCLUSIONThe system of secretory expressing bioactive peptide rAAV mediated gene transfer may be used to express efficiently exogenous gene in corporal cavernosum smooth muscle cells and affect cAMP level in the corporal cavernosum smooth muscle cells of the rat.

Animals ; Calcitonin Gene-Related Peptide ; biosynthesis ; genetics ; Cells, Cultured ; Cyclic AMP ; metabolism ; Cyclic GMP ; metabolism ; Dependovirus ; genetics ; Male ; Muscle, Smooth ; cytology ; metabolism ; Penis ; metabolism ; Rats ; Rats, Sprague-Dawley ; Recombination, Genetic ; Transfection