BACKGROUNDTo date, there have been no reports on altered nitric oxide (NO) content in ischemia/reperfusion with regard to in vivo preconditioning procedures. These studies are important for understanding the mechanisms of NO during early myocardial ischemic preconditioning. The aim of the present study was to investigate the mechanisms of NO during early myocardial ischemic preconditioning by measuring levels of NO and cyclic guanosine monophosphate (cGMP), as well as activity of nitric oxide synthase (NOS) in ischemia/reperfusion with respect to preconditioning in rats.

METHODSSixty-six female Sprague-Dawley rats were randomly divided into four groups: ischemic preconditioning group (IP), ischemia/reperfusion group (I/R), control group (CON), and preconditioning procedure group (PC). In the PC group, rats were further divided into PC1-, PC1 +, PC2-, PC2 +, PC3-, and PC3 + subgroups. Rats underwent left coronary artery occlusion and reperfusion, and subsequently, NOS activity and levels were assessed with spectrophotometric analysis. cGMP contents were measured with radioimmunoassay.

RESULTSThe level of NO and cGMP, as well as the activity of NOS, were significantly higher in the IP group compared to the I/R and CON groups (P < 0.05). During preconditioning prior to prolonged ischemia, NO and cGMP levels varied markedly with ischemia and reperfusion. The levels of NO repeatedly increased when the heart was exposed to three episodes of 5-minute ischemia, and were almost completely reversed during each reperfusion period. NO and cGMP levels were significantly different between the 5-minute period of ischemia and the same period of reperfusion during preconditioning.

CONCLUSIONSNO plays an important role during early phase myocardial ischemic preconditioning in rats. NO and cGMP could be triggers and mediators of early phase myocardial ischemic preconditioning. Altered NOS activity following ischemic stress could be the primary inducer of higher NO levels detected. NO and cGMP fluctuations might be the trigger for protection during early phase myocardial ischemic preconditioning.

Animals ; Cyclic GMP ; analysis ; Female ; Ischemic Preconditioning, Myocardial ; Nitric Oxide ; analysis ; physiology ; Nitric Oxide Synthase ; metabolism ; Rats ; Rats, Sprague-Dawley

OBJECTIVE: To observe the curative effect of Jieminqufeng decoction to the rats of allergic rhinitis and study the mechanism by which it treats allergic rhinitis. METHOD: Forty wistar rats were divided into 4 groups at random. There are Jieminqufeng decoction group, cetirizine group, model control group and normal control group. The rats of allergic rhinitis were established with ovalbumin. We surveyed the behavioral changes of rats, searched eosinophilic granulocytes in the nasal secretion, detected the contents of cAMP and cGMP in the blood plasma and nasal mucosa. RESULT: The model control group had typical symptoms of allergic rhinitis and the eosinophilic granulocytes could be found more frequently. The contents of cAMP and cAMP/cGMP rose in the blood plasma and nasal mucosa (P < 0.01). However, the changes of jieminqufeng decoction group were small. CONCLUSION The jieminqufeng decoction is an effective drug to allergic rhinitis. Its possible mechanism is that it changes the contents of cAMP and cGMP, lessens inflammatory reaction and blocks up the allergy.
Animals ; Anti-Inflammatory Agents ; therapeutic use ; Cyclic AMP ; analysis ; Cyclic GMP ; analysis ; Drugs, Chinese Herbal ; therapeutic use ; Male ; Phytotherapy ; Rats ; Rats, Wistar ; Rhinitis, Allergic, Perennial ; drug therapy

BACKGROUNDThe form deprivation (FD) reduces spatial contrasts and induces myopia. Nitric oxide and cyclic guanosine monophosphate (cGMP) are involved in visual signal transmission. This study investigated changes in nitric oxide synthase (NOS) activity and cGMP concentration in ocular tissues in acute and chronic form deprivation myopia.

METHODSGuinea pigs had one eye covered by translucent glass for 7, 14 or 21 days. Untreated litter mates were used as controls. NOS activity and cGMP concentrations in the retinal, choroidal and scleral tissues of FD eyes and control eyes were analyzed by radioimmunoassay after various durations of FD. The expression of NOS subtypes was identified by immunohistochemistry.

RESULTSMyopia was successfully induced in FD eyes after 14 days. Compared with control groups, the retinal NOS activity and cGMP concentrations in the FD eyes significantly increased after 14 and 21 days while the retinal NOS activity in the FD eyes was transiently suppressed by 7 days of FD. The NOS activity and cGMP concentrations of choroid and sclera in the FD eyes were higher than in the control groups at 21 days. The three isoenzymes of nitric oxide synthase were detected in the ocular tissues of guinea pigs.

CONCLUSIONSThe NOS activity and cGMP concentrations were upregulated after chronic FD and the retinal NOS activity was transiently suppressed at acute FD. The function of elevated NOS activity may be mediated by cGMP.

Animals ; Cyclic GMP ; analysis ; Guinea Pigs ; Immunohistochemistry ; Myopia ; metabolism ; Nitric Oxide ; physiology ; Nitric Oxide Synthase ; metabolism ; Refractive Errors ; Retina ; metabolism

OBJECTIVETo investigate the dynamics of plasma cAMP/cGMP in patients during cardiac surgery, and its relationship to traumatic stress.

METHODSSixteen patients, aged 19.31 years+/-10.4 years, who underwent an open heart operation with cardiopulmonary bypass (CPB) and hypothermia were served as subjects. The arterial plasma concentrations of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) were measured by radioimmunoassay 2 hours before operation, after heparinization, 20 minutes following CPB, at the end of the operation, and 24 and 72 hours postoperatively, respectively. The patients' preoperative blood samples were heparinized and the venous blood samples of 30 healthy blood donors were taken to measure the levels of cAMP and cGMP as heparin and normal controls separately.

RESULTSThere were no statistical difference among the heparin control, preoperative level and normal control. The peak values of cAMP and cGMP occurred during CPB and plasma cAMP levels changed synchronously with intensities of operative stimulus to human body. However cGMP level was mainly related to the operative stimulus to the heart and CPB. The cAMP value was positively correlated with the cGMP value (r=0.6313, P<0.001).

CONCLUSIONSDynamic variation of plasma cyclic ribonucleotide can be considered as a reference parameter for intensity of traumatic stress.

Adolescent ; Adult ; Biomarkers ; analysis ; Cardiopulmonary Bypass ; Coronary Disease ; blood ; surgery ; Cyclic AMP ; analysis ; blood ; Cyclic GMP ; analysis ; blood ; Female ; Humans ; Linear Models ; Male ; Middle Aged ; Multivariate Analysis ; Postoperative Period ; Preoperative Care ; Radioimmunoassay ; Reference Values ; Sensitivity and Specificity ; Stress, Psychological ; blood

This study was undertaken to observe the effects of organic or inorganic calcium antagonists and to investigate the involvement of cyclic nucleotides in regulating the vascular tone in the chorionic artery from normal or preeclamptic placenta. KCI and prostaglandin (PG) F2 alpha produced marked and constant contractions in chorionic arterial preparations of both normal and preeclamptic placentas. Nifedipine (NIF), verapamil (VER) and diltiazem (DIL) reduced the tension that had been produced by KCI and PGF2 alpha in a concentration-dependent fashion in both preparations, and the potency order of the three agents was NIF> VER > DIL. In preeclamptic arteries, however, the magnitudes of vasodilatation induced by NIF and DIL were much smaller than those in normal chorionic arteries. Mg2+ and Cd2+ also relaxed the tension induced by KCI and PGF2 alpha. In preeclamptic chorionic artery, the vasodilatation induced by Mg2+ was significantly potentiated, while that by Cd2+ was not. Removing endothelium did not alter cyclic GMP content in both preparations. In both preparations contracted by PGF2 alpha, nitroprusside markedly increased cyclic GMP content, but neither cyclic GMP nor cyclic AMP content was affected by acetylcholine, NIF, isopro-terenol, or Mg2+. The above results suggest that neither cyclic AMP nor cyclic GMP is involved in regulating the vascular tone of chorionic artery and that sensitivity of the artery in preeclampsia to the inhibitory action of calcium antagonist might be different from that in normal placenta.
Arteries/physiopathology ; Calcium Channel Blockers/*pharmacology ; Cyclic AMP/analysis ; Cyclic GMP/analysis ; Dinoprost/pharmacology ; Female ; Human ; Placenta/*blood supply ; Potassium Chloride/pharmacology ; Pre-Eclampsia/*physiopathology ; Pregnancy ; Vasoconstriction/*drug effects

PURPOSE: The effects of amiloride on cellular toxicity caused by tissue plasminogen activator (tPA) in mouse primary retinal cells were investigated. METHODS: Primary retinal cell cultures were maintained using glial conditioned medium. Commercial tPA and L-arginine were added, and the level of cyclic guanosine monophosphate (cyclic-GMP) in the culture supernatant was assessed using an ELISA assay. We measured the cell viability of cultured retinal cells pretreated with three different concentrations of amiloride (1, 10, and 100 microm) in addition to commercial tPA or L-arginine treatment. RESULTS: After exposing the cultured mouse retinal cells to tPA plus L-arginine or L-arginine alone, cyclic-GMP concentrations were 61.9 +/- 5.1 pmole/mL and 63.1 +/- 6.1 pmole/mL, respectively. However, the control group had a significantly lower concentration of cyclic-GMP (37.2 +/- 3.4 pmole/mL, p < 0.01). The cyclic GMP-dissolved solution did not cause retinal cell death. In the control group and the group treated with 1 microm amiloride and tPA containing L-arginine, the cell viability was 43.7% and 44.5%, respectively. However, cell viability increased to 70.6% with 10 microm amiloride and 78.4% with 100 microm amiloride (p = 0.015). CONCLUSIONS: L-arginine increases intracellular cyclic-GMP and may give rise to retinal cells through this mechanism. In addition, amiloride in concentrations greater than 10 microm protects against L-arginine-induced retinal cell death.
Amiloride/*pharmacology ; Analysis of Variance ; Animals ; Arginine/toxicity ; Cell Death/drug effects ; Cells, Cultured ; Cyclic GMP/pharmacology ; Enzyme-Linked Immunosorbent Assay ; Mice ; Retina/cytology/*drug effects ; Tissue Plasminogen Activator/*toxicity

OBJECTIVETo explore the effect and the mechanism of moxibustion for treatment of diabetic erectile dysfunction (ED).

METHODSDiabetes mellitus (DM) rat model was induced by streptozotozin (STZ) and then penis erectile experiment of apomorphine (APO) was used to select diabetic ED rats model, which were divided into 2 groups: a model group and a moxibustion group, with another normal control group set up. The moxibustion group were treated with moxibustion at "Shenshu" (BL 23) and "Sanyinjiao" (SP 6) with small moxa cone about the size of a wheat grain. The effects on penis erectile, blood sugar and total NOS, cNOS, iNOS, and cGMP were investigated.

RESULTSMoxibustion had a certain improving action on blood sugar, improved significantly erectile function, and more significantly increased NOS, cNOS, iNOS activities and cGMP contents in the penis.

CONCLUSIONMoxibustion has a certain action on the erectile function in the diabetic ED rats, which is related with improvement of blood sugar and promoting NO-cGMP pathway.

Animals ; Blood Glucose ; analysis ; Cyclic GMP ; physiology ; Diabetes Complications ; therapy ; Diabetes Mellitus, Experimental ; complications ; Erectile Dysfunction ; therapy ; Male ; Moxibustion ; methods ; Nitric Oxide ; physiology ; Rats ; Rats, Sprague-Dawley ; Signal Transduction

BACKGROUNDAngiotensin II (Ang II) acting at angiotensin AT(1) receptor (AT(1)R) has well documented effects on cardiovascular structure such as the promotion of cardiovascular hypertrophy and fibrosis, which are believed to be opposed by angiotensin AT(2) receptor (AT(2)R) stimulation. The expressions of AT(1)R and AT(2)R are up-regulated in senescent hearts. The purpose of this study was to investigate the interaction of signal transduction between AT(1)R and AT(2)R, and to detect whether there is any difference in the interaction in rat hearts of different age.

METHODSIn 3.5-, 12-, 18- and 24-month-old rats, the heart cell membrane activities of protein kinase C (PKC) and tyrosine kinase were measured when AT(1)R and AT(2)R were both activated by Ang II or just the AT(1)R was activated by Ang II and PD123319. The activities of cytosolic phospholipase A(2) (cPLA(2)) and the levels of cGMP were investigated when AT(1)R and AT(2)R were both activated by Ang II or just the AT(2)R was activated by Ang II and losartan.

RESULTSWhen AT(1)R and AT(2)R were both activated compared to when the AT(1)R was activated, the activities of PKC were not different in hearts from 3.5- and 12-month-old rats, but decreased significantly in 18- and 24-month-old rats; the activities of tyrosine kinase were not different in 3.5-month-old rats but decreased significantly in 12-, 18- and 24-month-old rats. The activities of cPLA(2) were all decreased significantly in rats of different age when AT(1)R and AT(2)R were both activated compared to when the AT(2)R was activated. Treatment with Ang II alone compared to Ang II and losartan decreased the levels of cGMP (fmol/mg) in rats of different age (102.7 +/- 12.7 versus 86.0 +/- 8.0 in 3.5-month-old rats, P < 0.05; 81.0 +/- 9.4 versus 70.0 +/- 6.3 in 12-month-old rats, P < 0.05; 69.8 +/- 5.6 versus 54.2 +/- 5.3 in 18-month-old rats, P < 0.01; 57.7 +/- 8.0 versus 39.0 +/- 3.0 in 24-month-old rats, P < 0.01).

CONCLUSIONSThe activation of AT(1)R inhibited the signal transduction of AT(2)R during the aging variation, and the activation of AT(2)R inhibited the signal transduction of AT(1)R in rat heart of different age.

Aging ; metabolism ; Animals ; Cyclic GMP ; analysis ; Male ; Myocardium ; metabolism ; Phospholipases A2 ; metabolism ; Protein Kinase C ; metabolism ; Protein-Tyrosine Kinases ; metabolism ; Rats ; Rats, Sprague-Dawley ; Receptor, Angiotensin, Type 1 ; physiology ; Receptor, Angiotensin, Type 2 ; physiology ; Signal Transduction ; physiology

OBJECTIVETo investigate the role of endogenous carbon monoxide (CO) in hypoxia.

METHODSAfter rats were inhaled with hypoxic gases and the heme oxygenase inhibitor ZnPPIX was administered, we measured the CO levels in plasma, liver, lung and kidney. Meanwhile plasma cGMP levels were observed. Furthermore, we recorded the change of hemodynamic and blood gases.

RESULTSAcute mild hypoxia (10% O2) significantly increaed CO levels in plasma as well as liver, kidney and lung, while acute severe hypoxia (5% O2) significantly decreased CO levels in plasma as well as liver, kidney and lung. In addition, the former significantly elevated cGMP levels in plasma while the latter markedly reduced cGMP levels in plasma. The hemodynamic change occurred in accordance with the changes carbon monoxide.

CONCLUSIONOur results indicate, for the first time, that the endogenous carbon monoxide plays an important role in regulating the vessel tone during hypoxia.

Acute Disease ; Animals ; Blood Gas Analysis ; Carbon Monoxide ; blood ; metabolism ; Cyclic GMP ; blood ; Heme Oxygenase (Decyclizing) ; antagonists & inhibitors ; Hemodynamics ; Hypoxia ; metabolism ; physiopathology ; Kidney ; metabolism ; Liver ; metabolism ; Lung ; metabolism ; Rats ; Rats, Wistar

To investigate the effect of S-nitrosoglutathione (GSNO), a nitric oxide donor, on platelet production from megakaryocytes differentiated from cord blood CD34(+) cells in vitro, the CD34 (+) cells from eight fresh umbilical cord blood samples by a high-gradient magnetic cell sorting (MACS) system were cultured in serum-free medium for 14 d with thrombopoietin (TPO) 50 ng/ml, IL-3 10 ng/ml, stem cell factor (SCF) 50 ng/ml and rHuGM-CSF 20 ng/ml. Then, CD61 (+) cells were purified by MACS system from these CD34 (+) cells, and were cultured in serum-free medium supplemented with TPO 50 ng/ml, IL-3 10 ng/ml and SCF 50 ng/ml in the presence (treatment group) and absence (control group) of GSNO for 30 min or 2 h. Platelet-sized particles were counted by flow cytometry; megakaryocyte structure was detected by scanning electron microscope. Aggregation of the thrombin-induced platelet particle was observed under inversion microscope. cGMP was assessed by commercial ELISA kit. The results showed that, compared with the control group, the number of platelet-sized particles significantly increased (P<0.05) in the treatment group, in which megakaryocytes presented significant pseudopod formation and extensive membrane blebbing. The platelet particle aggregation could be observed under microscope after thrombin induction. cGMP activity was significantly increased after treatment with GSNO (P<0.05). These results propose that GSNO can facilitate platelet production from megakaryocyte, and it may be partly through cGMP pathway.
Antigens, CD34 ; analysis ; Blood Platelets ; cytology ; Cell Differentiation ; drug effects ; Cyclic GMP ; blood ; Female ; Fetal Blood ; cytology ; Hematopoiesis ; drug effects ; Hematopoietic Stem Cells ; cytology ; Humans ; Megakaryocytes ; cytology ; Nitric Oxide ; physiology ; Platelet Aggregation ; drug effects ; Pregnancy ; S-Nitrosoglutathione ; pharmacology