Effect of resistance exercise on peripheral inflammatory biomarkers in healthy adults: a meta-analysis of randomized controlled trials

OBJECTIVE

This study aimed to evaluate the effect of resistance exercise on peripheral inflammatory biomarkers in healthy adults.

MATERIALS AND METHODS

Four databases, including PubMed, Web of Science, Cochrane Library, and SPORTDiscus, were searched from inception until April 1st, 2022. A meta-analysis was conducted using a random-effects model, followed by sensitivity analysis, subgroup analysis, meta-regression analysis, and publication bias analysis.

RESULTS

15 randomized controlled trials were included in the meta-analysis. The pooled results showed that resistance exercise significantly decreased TNF-α levels (SMD = -0.81, 95% CI: -1.42 to -0.20, p = 0.009) but did not affect IL-6 and CRP levels. Individuals with BMI 18.5-24.9 exhibited significantly decreased IL-6 levels, while moderate strength resistance exercise could significantly decrease TNF-α levels. Finally, age might be a confounding factor influencing the effect of resistance exercise on IL-6.

CONCLUSIONS

Resistance exercise could reduce TNF-α levels in healthy adults, and resistance exercise with moderate intensity could reduce TNF-α levels more effectively.

Effects of aerobic exercise on inflammatory factors in healthy adults: a meta-analysis

OBJECTIVE

With this meta-analysis we aimed at systematically evaluating the intervention effects of aerobic exercise on inflammatory factors in healthy adults and identifying an optimal aerobic exercise program with anti-inflammatory effects.

MATERIALS AND METHODS

Four databases, including PubMed, Web of Science, Cochrane Library and SPORTDiscus, were searched from inception until April 30, 2021. Stata version 11.0 was used for data analysis.

RESULTS

A total of 15 studies with 1160 participants were included. The pooled estimates showed that aerobic exercise could significantly reduce TNFα levels (SMD=-0.30, 95% CI: -0.58 - -0.03, p=0.032), while the levels of IL-6 (SMD=-0.14, 95% CI: -0.32-0.03, p=0.109) and CRP (SMD=-0.09, 95% CI: -0.34-0.16, p=0.484) were not significantly affected.

CONCLUSIONS

Aerobic exercise exerts a positive effect by preventing inflammation-related diseases.

MicroRNA-1271 inhibits the progression of papillary thyroid carcinoma by targeting IRS1 and inactivating AKT pathway

OBJECTIVE

The important role of microRNA-1271 (miR-1271) has been identified in human diseases and cancers. However, the biological function of miR-1271 remains ambiguous in papillary thyroid carcinoma (PTC). Therefore, the specific role of miR-1271 was investigated in PTC.

PATIENTS AND METHODS

The expressions of miR-1271 and insulin receptor substrate 1 (IRS1) were detected by quantitative Real Time-Polymerase Chain Reaction (qRT-PCR) assay. The protein expression of the genes was measured by Western blot analysis. The function of miR-1271 was investigated using methyl thiazolyl tetrazolium (MTT) and transwell assays. The Dual-Luciferase assay was used to observe the relationship between miR-1271 and IRS1.

RESULTS

MiR-1271 was downregulated in PTC tissues. Moreover, overexpression of miR-1271 suppressed migration, invasion and proliferation of PTC cells. Furthermore, IRS1 was indicated as a direct target gene of miR-1271 and knockdown of IRS1 inhibited cell migration, invasion and proliferation in PTC. In addition, miR-1271 inhibited the progression of PTC by targeting IRS1. Besides that, miR-1271 blocked the epithelial-mesenchymal transition (EMT) and protein kinase B (AKT) pathway in PTC.

CONCLUSIONS

MiR-1271 inhibited the progression of PTC by targeting IRS1 and blocking EMT and AKT pathway.

[-a]

Objective: To investigate the clinicopathological features, treatment and prognosis of fibrin-associated diffuse large B cell lymphoma (DLBCL) arising within concurrent atrial myxoma. Methods: Six cases of fibrin-associated DLBCL arising within concurrent atrial myxoma diagnosed at the Department of Pathology, Guangdong General Hospital, from 2006 to 2019 were included. The histology, immunophenotype, treatment and prognoses were analyzed. Results: The patients' age ranged from 46 to 78 years (mean 59 years). There were 3 males and 3 females. The tumors were all discovered incidentally on histological examination of surgical pathology specimens excised for atrial myxoma. All patients appeared to have morphological features of DLBCL, B lineage immunophenotype, high proliferative index and latency type III of Epstein-Barr viral infection. They had complete tumor resections without adjuvant chemotherapy and were healthy at 5- to 120-month follow-ups. Conclusions: Fibrin-associated DLBCL arising within concurrent atrial myxoma is an unusual form of DLBCL associated with chronic inflammation, and its clinical outcome is indolent. The findings suggest that this type of lymphoma does not warrant excessive or unnecessary treatments after complete resection.

[Diagnostic and prognostic implications of MAML2 gene translocation in primary pulmonary mucoepidermoid carcinoma]

Objective: To investigate MAML2 gene-translocation in primary pulmonary mucoepidermoid carcinoma (PMEC) and pulmanary adenosquamous carcinoma, and the optimal diagnostic immunohistiochemical (IHC) panel in distinguishing PMEC from adenosqumous carcinoma. Methods: Twenty-four cases of PMEC and 44 adenosqumous carcinoma diagnosed in the Guangdong General Hospital were tested for MAML2 translocation by fluorescent in-situ hybridization (FISH) using tissue array. An IHC panel including TTF1, Napsin A, CK5/6, p63, p40 and Ki-67 was performed on the cohort. The clinical data for all cases were collected and all PMEC patients had follow-up information. Results: The patients' age ranged form 6 to 73 years, with a median age of 32 years. The male to female ratio was 1.4∶1.0. MAML2 translocation was found in 16/24 (66.7%) cases of PMEC whereas all 44 cases adenosqumous carcinoma were negative for translocation. All the cases of the PMEC were negative for TTF1 and Napsin A but positive for CK5/6, p63 and p40 in the intermediate cells and epidermal-like cells. In most PMEC cases, the Ki-67 expression index was lower than 10%. In contrast, most cases of adenosqumous carcinomas expressed TTF1 and Napsin A in the adenomatous component and CK5/6, p63 and p40 in the squamous component, which expression pattern was different from that of PMEC. Based on IHC staining, 2 cases of highly invasive ALK-positive adenocarcinoma mimicing PMEC were also found in the study. Conclusions: MAML2 gene translocation can be detected in about two-third of PMEC. Translocation of MAML2 gene and lower morphology grading are associated with good prognosis. The combined use of IHC antibodies panel is helpful to distinguish PMEC from the adenosqumous carcinoma and adenocarcinoma mimicing PMEC.

[Pathological features of duodenal-type follicular lymphoma]

Objective: To investigate the clinicopathological features, treatment and prognosis of duodenal-type follicular lymphoma. Methods: Four cases of duodenal-type follicular lymphoma diagnosed at Guangdong General Hospital from 2014 to 2015 with detailed clinical data were included. The histomorphology, immunophenotype, treatment and prognoses were analyzed. Results: The patients' age ranged from 51 to 57 years (mean 54 years), and there were 2 males and 2 females. The involved sites were gastric fundus in one case, second portion of the duodenum in two cases and terminal ileum in one case. All patients presented with multiple mucosal granules or nodules at endoscopy. Microscopically, there were multiple mucosal neoplastic follicles, constituting grade 1-2 disease based on nodal follicular lymphoma grading system. The tumor cells were positive for CD20, CD10, bcl-6 and bcl-2. CD21 highlighted the follicular dendritic meshwork mainly at the periphery of the follicles. Proliferation index was low. Three patients received rituximab monotherapy for 4 cycles, leading to complete remission. One patient refused therapy and the disease progressed to systemic lymphoma 15 months after the initial diagnosis. Conclusions: Duodenal-type follicular lymphoma is a special variant of follicular lymphoma with indolent clinical course. The tumor exhibits morphology of low grade follicular lymphoma with characteristic dendritic meshwork at the periphery of the follicles and a low proliferation index. Prognosis is excellent. Rituximab monotherapy is treatment of choice, but a small minority of patients may progress to systemic disease.

[Expression of βF1 and T cell receptor γ in T lymphoblastic lymphoma/leukemia]

Objective: To evaluate the expression of βF1 and T cell receptor (TCR)γ in T lymphoblastic lymphoma/leukemia(T-LBL/ALL), and investigate the clinicopathological features. Methods: Fifty-one cases of T-LBL/ALL were collected at Guangdong General Hospital from 2010 to 2016, the expression of βF1 and TCRγ was assessed by immunohistochemistry. Results: There were 13 cases of children and adolescents, and 38 cases of adults. The expression rates of βF1 and TCRγ were 27.5%(14/51) and 15.7%(8/51) respectively. The proportion of adults in αβ T-LBL/ALL, TCR-silent T-LBL/ALL and γδ T-LBL/ALL was 7/14, 79.3%(23/29)and 8/8 respectively, and the difference was significant (P=0.023). There was no statistical difference in sex, LDH, bone marrow involvement and Ann arbor stage among these three groups(P>0.05). γδ T-LBL/ALLs included 6 cases of CD4(-)/CD8(-) phenotype, whereas αβ T-LBL/ALL included 7 cases of CD4(+) /CD8(+) phenotype. There was significant difference in CD4/CD8 expression among these three groups(P<0.01). Conclusions: γδ T-LBL/ALL occurred only in adults, with predominantly CD4(-)/CD8(-) phenotype. αβ T-LBL/ALL occurred more common in children and adolescents, with predominantly CD4(+) /CD8(+) phenotype.

[Serum uric acid is associated with disease severity and an important predictor for clinical outcome in patients with pulmonary hypertension]

Objective: The growing body of literature showed a link between uric acid and pulmonary hypertension (PH), but the impact of hyperuremia on outcome of patients with PH has not been well defined. Therefore, the present study was performed to analyze the impact of uric acid on outcome of PH patients. Methods: One hundred seventy-three PH patients (112 females, mean age 38 years old), who were hospitalized in our department between January 2010 and December 2015, were included in our study, the PH diagnosis was made based on right heart catheterization examination result (mean pulmonary artery pressure≥25 mmHg(1 mmHg=0.133 kPa)). PH patients were divided into mild to moderate PH group (Rp/Rs≤0.6, n=97) and severe PH group (Rp/Rs>0.6, n=76). Fifty-one patients (33 females, mean age 45 years old) without PH based on right heart catheterization were included as control subjects. All participants were followed up for a median of 24 months(6-71 months). Clinical endpoints were defined as cardiogenic death or heart-and-lung transplantation. Results: Uric acid was positively correlated with pulmonary vascular resistance(r=0.398, P<0.01), systemic vascular resistance(r=0.244, P<0.01) and mean right atrial pressure (r=0.26, P<0.01), and was negatively correlated with cardiac index(r=-0.278, P<0.01)and mixed venous oxygen saturation (r=-0.322, P<0.01)in PH patients. Serum uric acid level was significantly higher in patients with severe PH than in patients with mild-to-moderate PH and the control subjects (both P<0.05). According to the receiver operating characteristic curve (ROC), 425.5 μmol/L was found to be the best cut-off value of serum uric acid level to predict the outcome of PH patients (sensitivity 50%, specificity 72%). During follow-up, patients with higher level of uric acid (>425.5 μmol/L) were linked with poorer clinical outcome compared to patients with uric acid <425.5 μmol/L(P=0.027). Conclusion: Our findings suggests that uric acid is associated with the severity of PH and higher uric acid level serves as an important predictor for poor clinical outcome of PH patients.

Perivascular epithelioid cell tumor (PEComa) of gynecologic origin: a clinicopathological study of three cases

Perivascular epithelioid cell tumors (PEComas), occasionally associated with the tuberous sclerosis complex, are characterized by varying amounts of spindle and epithelioid cells with clear to eosinophilic cytoplasm that display immunoreactivity for melanocytic markers, most frequently HMB-45. Perivascular epithelioid cell tumor of gynecologic origin is very rare, and there have been only a few reported cases. This study describes the clinical, histological, and immunohistochemical features and prognoses of three cases of gynecologic origin. Two of the three tumors were confined to the uterus and one to the vagina. None of the patients had tuberous sclerosis complex. Immunohistochemistry indicated that all three cases expressed at least one melanocytic marker, and HMB45 was a positive marker for all of them. These markers can be found in both epithelial cells and spindle cells. Except for MiTF, which was located in the nucleus, all the other antibodies were located in the cytoplasm. The three cases have been followed up for 26, 22, and three months, respectively, with disease-free survival in all cases. We conclude that PEComas of gynecologic origin have morphological and immunohistochemical features of the PEComa family, which are rare and should be included in the differential diagnosis with other tumors. Until more cases of this rare tumor are evaluated with longer follow-up, firm criteria for malignancy remain uncertain.

Prognostic significance of cyclinD1 amplification and the co-alteration of cyclinD1/pRb/ppRb in patients with esophageal squamous cell carcinoma

CyclinD1/pRb/ppRb is one of the most important pathways regulating the cell cycle, and related with the development of many cancers. However, the co-alteration of CyclinD1/pRb/ppRb in esophageal squamous cell carcinomas is less understood. This study aims to analyze the combined prognostic significance of cyclinD1 (CCND1) DNA amplification and the co-alteration of CCND1/pRb/ppRB in patients with esophageal squamous cell carcinoma. CCND1 DNA amplification and the protein expression of CCND1, pRb, and ppRb on 100 tumor specimens and 11 normal tissues were detected using real-time quantitative reverse transcription polymerase chain reaction and immunohistochemistry, respectively. Their prognosis significance was analyzed by Kaplan-Meier method. We found that 41% of the patients had CCND1 DNA amplification, which had a short survival time compared with the patients without CCND1 amplification (25.63 months vs. not reached, P=0.007). The patients with the co-alternation of CCND1(+) /pRb(-) /ppRb(+) protein expression levels have a poorer overall survival than the others (11.4 vs. 43.4 months, P=0.001). Cox regression analysis showed that the co-alternation of CCND1/pRb/ppRb and CyclinD1 amplification were the two most independent prognosis factors of patients with esophageal cancer. These findings suggested that CCND1 amplification and co-alternation of CCND1(+) /pRb(-) /ppRb(+) may play a crucial role in the prognostic evaluation of patients with esophageal cancer, and the patients with CCND1(+) /pRb(-) /ppRb(+) have the worst prognosis in all the patients. The results also indicated that the patients with CCND1 amplification or co-alternation of CyclinD1(+) /pRb(-) /ppRb(+) might be the preponderant people for therapy targeting the CCND1/pRb/ppRb pathway in the future.

Defect complexes in Re3+-doped magnesium sulphate phosphors

A series of magnesium sulphate phosphors MgSO4:RE3+,X ( RE = Dy, Tm, Eu and X = P, Mn) have been prepared and studied. Based on the experimental results of thermoluminescence (TL) emission spectra and dose responses studies, it is proposed that in these phosphors large defect complexes are formed, which include intrinsic imperfections and dopants. These defect complexes were formed in the course of preparation of phosphors and could be regarded as basic elements in the TL multi-stage processes. This defect model might be applicable to the most of TL materials.

TL and OSL of SrSO4 phosphors doped with Eu

The thermoluminescence (TL) and optically stimulated luminescence (OSL) of SrSO4:Eu (0.1 mol%) powder sample were studied. The TL and OSL emission spectrum are measured after irradiation (absorbed dose 100 Gy) of 90Sr source; both of them showed that the emission wavelength is at approximately 375 nm, which indicates that TL and OSL have the same luminescence centres, and the luminescence comes from transitions between the energy levels of Eu2+. The TL glow curves and OSL decay curves illustrate that there is only one main TL peak but two main components in OSL curves. By a comparative study of TL and OSL it is concluded that OSL traps are different from TL traps. The TL and OSL dose responses of SrSO4:Eu phosphor were measured, and it showed that phosphor has similar dose responses for OSL and TL.

Thermoluminescence glow curves and optical stimulated luminescence of undoped alpha-Al2O3 crystals

The characteristics of thermoluminescence (TL) and optical stimulated luminescence (OSL) in undoped alpha-Al2O3 single crystals were studied. The TL glow curves of the crystal samples irradiated at various dose levels were measured by RisØ TL/OSL-DA-15B/C reader with U-340 or 7-59 filters at different heating rates. The glow peaks measured with U-340 at approximately 210 degrees C of the undoped alpha-Al2O3 can be well fitted by first-order kinetic equation whereas the glow peaks measured with 7-59 filters are a composite of two first-order glow peaks. It indicates that the TL glow curves are dependent upon the filter used in the reader that is related to the emission spectra of luminescence materials. The OSL were also measured and fitted by two exponential functions to get the luminescence intensities. The TL and OSL dose responses of the undoped alpha-Al2O3 crystal were obtained in the dose range of 0.12-248 Gy and fitted by the composite action dose-response function to get nonlinear characteristic parameters. The TL and OSL dose responses are linear-sublinear.

Thermoluminescence of MgSO4 doped with Eu and P impurities

CaSO4:Eu, MgSO4:Eu and MgSO4:Eu,P phosphors have been prepared and their thermoluminescence (TL) characteristics were studied. A main glow peak due to Eu2+ ions is seen at approximately 146 degrees C and 440 nm and glow peaks at approximately 145 degrees C, approximately 190 degrees C, approximately 260 degrees C and approximately 360 degrees C for 590 nm and 625 nm wavelengths are identified as Eu3+ ion emissions in MgSO4:Eu. Emission spectra in MgSO4:Eu and the MgSO4:Eu,P show that the MgSO4:Eu3+ glow peak at 260 degrees C for 590 nm and 625 nm shifts to 280 degrees C with enhanced intensity while the Eu2+ ion glow peak at 146 degrees C remains but with reduced intensity. The main glow peak at approximately 146 degrees C and 440 nm from Eu2+ ions shows significant difference from the characteristic glow peaks of Eu3+ ions. It is observed that the wavelength of the Eu2+ ion glow peak is inversely proportional to the radius of the cation of the host sulphate in alkaline-earth sulphate phosphors. By contrast the wavelengths of the Eu3+ ion glow peaks remain unchanged in different sulphates. Besides, the glow curve at approximately 146 degrees C obtained using a conventional blue sensitive reader shows simply the first order kinetics. It is concluded that the luminescence centres and distribution of traps related to Eu2+ ions are different from that of Eu3+ ions in MgSO4:Eu and MgSO4:Eu,P phosphors.

Non-linearity of TL dose responses in MgSO4:Dy CO-doped with Mn, P and Cu

Thermoluminescence (TL) dose responses to gamma radiation in the dose range from 0.1 Gy to 20 kGy in MgSO4:Dy, MgSO4:Dy,Mn, MgSO4:Dy,P and MgSO4:Dy,P,Cu phosphors were obtained and fitted by the composite action dose response function to obtain non-linear characteristic parameters, one-hit factor R and characteristic dose D0, which indicate that the TL dose responses for individual TL glow peaks in MgSO4:Dy, MgSO4:Dy,Mn and MgSO4:Dy,P phosphors all are supralinear. The non-linearity of dose response for the main dosimetric peak in MgSO4:Dy,P,Cu depends critically on the concentration of doped Cu and sublinearity can be obtained in the dose responses of TL materials doped with a certain amount of Cu. Based on studying the TL glow curves, dose responses and three dimension emission spectra of these phosphors, it is supposed that the TL event is generated via a multi-stage process within a large defect complex in doped magnesium sulphate phosphors. Doping with Cu results in reformation of the defect complex in which there is a strong spatial association between a trapping centre and a recombination centre so that the probability of one-hit TL events increases. The non-linearity of the dose responses is usually a difficulty for measuring higher dose in TL dosemeters. It can be overcome by enlarging the linear range of the dose-response or by calibrating the dose-response curves using non-linear characteristic parameters in a dose response function, such as the composite action dose response function.

Effects of matrine, artemisinin, tetrandrine on cytosolic [Ca2+]i in guinea pig ventricular myocytes

AIM

To compare the effects of matrine, artemisinin, and tetrandrine on intracellular Ca2+ concentration ([Ca2+]i) in guinea pig ventricular myocytes.

METHODS

A single ventricular myocyte was loaded with Fluo 3-acetoxymethyl (Fluo 3-AM). [Ca2+]i was recorded by laser scanning confocal microscope and represented by fluorescence intensity (FI).

RESULTS

1) KCl 60 mmol . L-1 elevated the FI from 299 +/ -19 to 1389 +/- 325 (P < 0.01) in the presence of extracellular Ca2+ 1.8 mmol . L-1. 2) Both matrine and artemisinin at the concentration of 100 micromol . L-1 could enhance the increase of FI by KCl 60 mmol . L-1. The FI values reached 1495 +/- 320 and 1646 +/- 308 from 301 +/- 14 and 299 +/- 16 (P < 0.01), respectively. 3) Both tetrandrine 1, 10, and 100 micromol . L-1 and verapamil 10 micromol . L-1 inhibited the influx of extracellular Ca2+ induced by KCl 60 mmol . L-1. 4) Matrine 1, 10, and 100 micromol . L-1 could elevate the FI in the presence of extracellular Ca2+. The FI values reached 441 +/- 96, 504 +/- 112, and 643 +/- 126 from 303 +/- 27, 300 +/- 32, and 296 +/- 19 (P < 0.05), respectively. 5) Tetrandrine 1 and 10 micromol . L-1 could apparently inhibited Ca2+ release from intracellular calcium stores induced by caffeine 20 mmol . L-1 (P < 0.05).

CONCLUSION

Effects of matrine, artemisinin, and tetrandrine on [Ca2+ )]i in ventricular

Effects of erysimin G on renal tubular function and 70-pS K+ channel activity of thick ascending limb

AIM

To study the effect of erysimin G (CH35H52O13) on the thick ascending limb (TAL) 70-pS K+ channel of rat kidney and its effect on diuresis.

METHODS

The patch-clamp cell-attached recording technique was used to record the single potassium channel current, and the urine volume (UV) was measured by urethral intubation to determine the diuretic effect.

RESULTS

Erysimin G can increase the urine volume and decrease the 70-pS potassium channel activity of TAL.

CONCLUSION

Erysimin G has a diuretic effect and its inhibition on the activity of apical 70-pS potassium channel may be the mechanism of its diuretic effect.

Artemisinin blocks activating and slowly activating K+ current in guinea pig ventricular myocytes

AIM

To study the effect of artemisinin (Art) on outward rectifier potassium current in ventricular myocytes.

METHODS

In isolated guinea pig ventricular myocytes, the effects of Art on the two components of delayed outward rectifier K+ current (IK), the rapidly activating inward K+ current (IKr), and the slowly rectifying outward K+ current (IKs) were observed by the whole cell patch-clamp technique.

RESULTS

Art decreased IK in a concentration-dependent manner. The IKstep and IKtail were reduced from 387 +/- 46 pA to 240 +/- 48 pA and from 299 +/- 30 pA to 130 +/- 38 pA, respectively at holding potential of +40 mV by Art 50 mumol.L-1. The envelope of tail analysis suggested that both IKr and IKs were inhibited.

CONCLUSION

Art blocked the two components of delayed outward rectifier K+ current (IKr and IKs) in guinea pig ventricular cells.

The bioconcentration of 131I in fresh water fish

The dynamic characteristics of the radionuclide concentration process in fresh water fish have been studied. The experimental data for the tilapias were fitted using a simple compartment model to get characteristic parameters such as concentration factors, elimination rate constants, and initial concentration rates, which are 3.08 Bq kg-1/Bq L-1, 0.00573 h-1, and 12.42 Bq kg-1 h-1, respectively. The relative concentrations of 131I in different parts, i.e., head, gills, flesh, bone and internal organs, of the tilapias are also determined, which are found to be 10.8, 15.4, 26.1, 11.0, and 37.0%, respectively. The effects of different factors on the transfer of radionuclides in fresh water fishes are also discussed. Experiments on the tilapias and the common carp show that the variation of concentration factors for different species may be significant even for the same radionuclide and the same ecological system. On the other hand, the variation in the concentration factors for the flesh of the tilapias is not significant for a certain range of 131I concentrations in the water.

Evoked tensions in rabbit aorta by emptying intracellular Ca2+ stores with cyclopiazonic acid, thapsigargin, and ryanodine

AIM

To study the increase of plasma membrane Ca2+ permeability in response to depletion of intracellular Ca2+ stores.

METHODS

In Ca(2+)-free medium, 2 selective inhibitors of sarcoplasmic reticulum (SR) Ca2+ pump ATPase, cyclopiazonic acid (CPA) and thapsigargin (Tha), and an activator of Ca(2+)-induced Ca2+ release channel (CICR), ryanodine (Rya), depleted intracellular Ca2+ stores sensitive to both caffeine and phenylephrine in rabbit aortic rings and caused sustained tensions when Ca2+ reintroduction. These tensions were taken as the increase of plasma Ca2+ permeability by depletion of intracellular Ca2+ stores.

RESULTS

The extracellular Ca(2+)-dependent tensions caused by Tha and Rya 3 mumol.L(-1) and CPA 30 mumol.L(-1) were 0.94, 1.1, and 0.14 g, respectively, and the tension caused by Rya was not inhibited by CPA.

CONCLUSION

(a) Besides the depletion of intracellular Ca2+ stores, an activated state of Ca2+ release channels in SR may also mediate the activation of Ca2+ influx from plasma membrane in rabbit aorta; (b) Rya needs caffeine to fully open CICR channel in SR.

Putative, selective inhibitors of sarcoplasmic reticulum Ca+(+)-pump ATPase inhibit relaxation by nitroglycerin and atrial natriuretic factor of the rabbit aorta contracted by phenylephrine

Using three putative, selective inhibitors of the Ca+(+)-pump ATPase of sarcoplasmic reticulum (SR), cyclopiazonic acid, thapsigargin and 2,5-di-(tert-butyl)-1,4-benzohydroquinone, the mechanisms of relaxation of the arterial smooth muscle by cyclic GMP-generating vasodilators were studied in the ring preparations of the rabbit aorta. Nitroglycerin (NTG) and atrial natriuretic factor (ANF) were used as representative cyclic GMP-generating vasodilators. When the above three inhibitors of SR Ca+(+)-pump ATPase were present during the period of reloading of intracellular store sites with Ca++, the phasic contractions induced by phenylephrine or caffeine in the succeeding period in Ca+(+)-free media containing 2 mM EGTA were inhibited in a concentration-dependent manner. With 3 x 10(-5) M of cyclopiazonic acid the inhibition was almost complete for both agonists. NTG and ANF relaxed the aorta contracted by phenylephrine (10(-6) M) and produced an increase in cyclic GMP content. All the three SR Ca+(+)-pump ATPase inhibitors produced a concentration-dependent inhibition of the relaxation by NTG and ANF without affecting the increment of cyclic GMP content. These results indicate that the proper functioning of SR Ca+(+)-pump ATPase is necessary for elicitation of relaxation by NTG and ANF. Enhanced sequestration of Ca++ by SR may be an important mechanism by which these compounds induce relaxation in this type of smooth muscle.