Relationship between low cardiorespiratory fitness and mortality in normal-weight, overweight, and obese men

CONTEXT

Recent guidelines for treatment of overweight and obesity include recommendations for risk stratification by disease conditions and cardiovascular disease (CVD) risk factors, but the role of physical inactivity is not prominent in these recommendations.

OBJECTIVE

To quantify the influence of low cardiorespiratory fitness, an objective marker of physical inactivity, on CVD and all-cause mortality in normal-weight, overweight, and obese men and compare low fitness with other mortality predictors.

DESIGN

Prospective observational data from the Aerobics Center Longitudinal Study.

SETTING

Preventive medicine clinic in Dallas, Tex.

PARTICIPANTS

A total of 25714 adult men (average age, 43.8 years [SD, 10.1 years]) who received a medical examination during 1970 to 1993, with mortality follow-up to December 31, 1994.

MAIN OUTCOME MEASURES

Cardiovascular disease and all-cause mortality based on mortality predictors (baseline CVD, type 2 diabetes mellitus, high serum cholesterol level, hypertension, current cigarette smoking, and low cardiorespiratory fitness) stratified by body mass index.

RESULTS

During the study period, there were 1025 deaths (439 due to CVD) during 258781 man-years of follow-up. Overweight and obese men with baseline CVD or CVD risk factors were at higher risk for all-cause and CVD mortality compared with normal-weight men without these predictors. Using normal-weight men without CVD as the referent, the strongest predictor of CVD death in obese men was baseline CVD (age- and examination year-adjusted relative risk [RR], 14.0; 95% confidence interval [CI], 9.4-20.8); RRs for obese men with diabetes mellitus, high cholesterol, hypertension, smoking, and low fitness were similar and ranged from 4.4 (95% CI, 2.7-7.1) for smoking to 5.0 (95% CI, 3.6-7.0) for low fitness. Relative risks for all-cause mortality in obese men ranged from 2.3 (95% CI, 1.7-2.9) for men with hypertension to 4.7 (95% CI, 3.6-6.1) for those with CVD at baseline. Relative risk for all-cause mortality in obese men with low fitness was 3.1 (95% CI, 2.5-3.8) and in obese men with diabetes mellitus 3.1 (95% CI, 2.3-4.2) and as slightly higher than the RRs for obese men who smoked or had high cholesterol levels. Low fitness was an independent predictor of mortality in all body mass index groups after adjustment for other mortality predictors. Approximately 50% (n = 1674) of obese men had low fitness, which led to a population-attributable risk of 39% for CVD mortality and 44% for all-cause mortality. Baseline CVD had population attributable risks of 51% and 27% for CVD and all-cause mortality, respectively.

CONCLUSIONS

In this analysis, low cardiorespiratory fitness was a strong and independent predictor of CVD and all-cause mortality and of comparable importance with that of diabetes mellitus and other CVD risk factors.

Variations of synaptotagmin I, synaptotagmin IV, and synaptophysin mRNA levels in rat hippocampus during the estrous cycle

Periodic changes in ovarian steroid levels during fertility cycles affect learning both in humans and in rats in parallel with electrophysiological and morphological fluctuations in selective neuronal populations. In particular, during the estrous cycle of the female rat, hippocampal CA1 region undergoes cyclic modifications in synaptic density. To investigate the molecular mechanisms involved in synaptic remodeling during the estrous cycle, we analyzed the expression of three presynaptic markers, synaptotagmin I, synaptotagmin IV, and synaptophysin, in the female adult rat brain by in situ hybridization. Relative abundance in mRNA for these three markers was quantified at four phases of the estrous cycle: diestrus, proestrus (AM and PM), and estrus. mRNA levels for syt1 exhibited cyclic variations in pyramidal neurons of the CA3 region of hippocampus during the estrous cycle, while mRNA levels for syt4 and SYN were relatively invariant in this or other regions of the hippocampus. Because CA3 pyramidal neurons make synaptic contacts in CA1, modulation of syt1 expression in CA3 may participate in the changes in synaptic density observed in CA1 during the estrous cycle. Furthermore, both syt1 and SYN mRNA varied cyclically in layer II, but not in layer III of entorhinal cortex, while syt4 remained unchanged throughout the cycle. These data suggest that regular variations in steroid hormone levels during fertility cycles may alter the properties of several networks involved in information processing and learning and memory through altered levels of presynaptic proteins.

Urinary bladder carcinogenicity of dimethylarsinic acid in male F344 rats

The present study was conducted to determine the carcinogenicity of dimethylarsinic acid (DMA) administered to male F344 rats in a 2 year bioassay. A total of 144 rats (10 weeks old at the start) were divided into four groups of 36 rats each. Groups 1-4 received DMA (purity 100%) at concentrations of 200, 50, 12.5 and 0 p.p.m. in the drinking water, respectively, for 104 weeks. From weeks 97 to 104, urinary bladder tumors were observed in 12 of 31, eight of 31 and none of 33 in groups 1-3, respectively. No bladder tumors were observed in group 4. The present study demonstrated that long-term p. o. administration of DMA induced urinary bladder carcinomas in male F344 rats. Therefore, the results indicate that DMA is carcinogenic for the rat urinary bladder, which may be related to the human carcinogenicity of arsenicals.

[Design of CXLY-II low frequency magnetic fields pulse generator]

An experimental device, low frequency magnetic fields pulse generator, has been designed and accomplished in our department. It can provide low frequency magnetic fields pulse with the intensity from 150mT to 800mT and the frequency from 0 to 100Hz. This device is easy to operate and performs reliably. It can stably work for a long time and has been successful used in the experiment of magnetic biological effect.

Specific p53 gene mutations in urinary bladder epithelium after the Chernobyl accident

After the Chernobyl accident, the incidence of urinary bladder cancers in the Ukraine population increased gradually from 26.2 to 36.1 per 100,000 between 1986 and 1996. Urinary bladder epithelium biopsied from 45 male patients with benign prostatic hyperplasia living in radiocontaminated areas of Ukraine demonstrated frequent severe urothelial dysplasia, carcinoma in situ, and a single invasive transitional cell carcinoma, combined with irradiation cystitis in 42 cases (93%). No neoplastic changes (carcinoma in situ or transitional cell carcinoma) were found in 10 patients from clean areas (areas without radiocontamination). DNA was extracted from the altered urothelium of selected paraffin-embedded specimens that showed obviously abnormal histology (3 cases) or intense p53 immunoreactivity (15 cases), and mutational analysis of exons 5-8 of the p53 gene was performed by PCR-single-strand conformational polymorphism analysis followed by DNA sequencing. Nine of 17 patients (53%) had one or more mutations in the altered urothelium. Urine sediment samples were also collected from the patients at 4-27 months after biopsy and analyzed by PCR-single-strand conformational polymorphism analysis or yeast functional assay, and identical or additional p53 mutations were found in four of five cases. Interestingly, a relative hot spot at codon 245 was found in five of nine (56%) cases with mutations, and 11 of the 13 mutations determined (73%) were G:C to A:T transitions at CpG dinucleotides, reported to be relatively infrequent (approximately 18%) in human urinary bladder cancers. Therefore, the frequent and specific p53 mutations found in these male patients may alert us to a future elevated occurrence of urinary bladder cancers in the radiocontaminated areas.

[Expression of vascular endothelial growth factor and tumor angiogenesis correlates with biological behaviors of nasopharyngeal carcinoma]

OBJECTIVE

To study the correlation between tumor angiogenesis and biological behaviors of nasopharyngeal carcinoma(NPC).

METHOD

Angiogenesis was assessed by the microvessel dinsity(MVD) and expression of vascular endothelial growth factor(VEGF) was detected using immunohistochemical S-P method. Paraffin-embedded specimens from 65 patients with NPC and 15 with benign nasopharyngeal tumors, 15 with tumor-free nasopharyngeal mucosac were detected.

RESULT

Expressions of VEGF and MVD in NPC group were higher than that of nonmetastic carcinoma group. The relationship between expressions of VEGF and MVD and the clinical staging present statistic significance.

CONCLUSION

MVD and expression of VEGF are highly correlated with biological behaviors of NPC, which may serve as a parameter for determining tumor biological metastatic potential and prognosis. Angiogenesis inhibitors might be helpful in preventing NPC from metastasis.

[The clinical significance of preserving superior epigastric vessels in Cohen incision]

OBJECTIVE

To study the clinical significance of preserving epigastric vessels in Cohen incision.

METHODS

42 cases of pregnant women were performed cesarean section using Cohen incision. One side vessel of incision was preserved, the other side was cut off. By self control comparison, skin temperature of two sides incision has been taken by CET (computer electric infrared thermograph) on the third day post operation. The thinkness of scar was measured with vernier calipers on the 40th day post operation.

RESULTS

The skin temperature difference between both sides of incision was (0.098 +/- 0.088) degree C. On the cut side the skin temperature was higher than that of the other side (P < 0.01). The scar thickness of cut side was (3.61 +/- 0.61) mm, the other side was (3.10 +/- 0.68) mm. The difference was significant (P < 0.01).

CONCLUSION

The inflammatory reaction and formation of scar can be decreased by means of preserving superior epigastric vessels in Cohen incision.

Interfacial bond strength of electrophoretically deposited hydroxyapatite coatings on metals

Hydroxyapatite (HAp) coatings were deposited onto substrates of metal biomaterials (Ti, Ti6Al4V, and 316L stainless steel) by electrophoretic deposition (EPD). Only ultra-high surface area HAp powder, prepared by the metathesis method 10Ca(NO3)2 + 6(NH4)2HPO4 + 8NH4OH), could produce dense coatings when sintered at 875-1000degreesC. Single EPD coatings cracked during sintering owing to the 15-18% sintering shrinkage, but the HAp did not decompose. The use of dual coatings (coat, sinter, coat, sinter) resolved the cracking problem. Scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) inspection revealed that the second coating filled in the "valleys" in the cracks of the first coating. The interfacial shear strength of the dual coatings was found, by ASTM F1044-87, to be approximately 12 MPa on a titanium substrate and approximately 22 MPa on 316L stainless steel, comparing quite favorably with the 34 MPa benchmark (the shear strength of bovine cortical bone was found to be 34 MPa). Stainless steel gave the better result since -316L (20.5 microm mK(-1)) > alpha-HAp (approximately 14 microm mK(-1)), resulting in residual compressive stresses in the coating, whereas alpha-titanium (approximately 10.3 microm mK(-1)) < alpha-HAp, resulting in residual tensile stresses in the coating.

LD-IgG, IgA, IgM complex in a postburn patient

A 4-year-old Chinese boy was admitted to our hospital with burns over 25% of his body. He had an extremely high LD activity (1743 U/l). LD isoenzyme analysis showed an abnormal band cathodic to LD-5. It was demonstrated by counter immunoelectrophoresis that the extra band was a complex of LD with IgG, IgA and IgM. Because LD-Ig complex is extremely rare in patients with burns, the clinical significance of this substance in blood remains unclarified.

Solution ripening of hydroxyapatite nanoparticles: effects on electrophoretic deposition

Electrophoretic deposition is a low-cost, simple, and flexible coating method for producing hydroxyapatite (Hap) coatings on metal implants. However, densification requires heating the coated metal to high temperatures, which, for commercial HAp powders, generally means at least 1200 degrees C. At such temperatures, the metal tends to react with the HAp coating, inducing decomposition, and the strength of titanium and stainless steel implants is severely degraded. With the use of raw uncalcined nanoparticulate Hap, densification can occur at 900 degrees -1050 degrees C; however, such coatings are prone to cracking due to the high drying shrinkage. This problem was solved by precipitating nanoparticulate HAp by the metathesis process [10Ca(NO3)2 + 6NH4H2PO4 + 8NH4OH] and optimizing the approximately 30 nm of nanoprecipitates by an Ostwald ripening approach, that is, by boiling and/or ambient aging in the mother liquor. While the as-precipitated nanoparticles produced severely cracked coatings, 2 h of boiling or 10 days of ambient aging ripened the "gel-like" mass into unagglomerated nanoparticles, which produced crack-free coatings. Since boiling enhanced particle size but ambient aging did not, crack elimination probably was due to the transition from the highly agglomerated gel-like state to the dispersed nanoparticulate state rather than to particle growth. Furthermore, boiling only reduced the amount of cracking whereas aging completely eliminated cracking.

Solution ripening of hydroxyapatite nanoparticles: effects on electrophoretic deposition

Electrophoretic deposition is a low-cost, simple, and flexible coating method for producing hydroxyapatite (Hap) coatings on metal implants. However, densification requires heating the coated metal to high temperatures, which, for commercial HAp powders, generally means at least 1200 degrees C. At such temperatures, the metal tends to react with the HAp coating, inducing decomposition, and the strength of titanium and stainless steel implants is severely degraded. With the use of raw uncalcined nanoparticulate Hap, densification can occur at 900 degrees -1050 degrees C; however, such coatings are prone to cracking due to the high drying shrinkage. This problem was solved by precipitating nanoparticulate HAp by the metathesis process [10Ca(NO3)2 + 6NH4H2PO4 + 8NH4OH] and optimizing the approximately 30 nm of nanoprecipitates by an Ostwald ripening approach, that is, by boiling and/or ambient aging in the mother liquor. While the as-precipitated nanoparticles produced severely cracked coatings, 2 h of boiling or 10 days of ambient aging ripened the "gel-like" mass into unagglomerated nanoparticles, which produced crack-free coatings. Since boiling enhanced particle size but ambient aging did not, crack elimination probably was due to the transition from the highly agglomerated gel-like state to the dispersed nanoparticulate state rather than to particle growth. Furthermore, boiling only reduced the amount of cracking whereas aging completely eliminated cracking.

The association between cardiorespiratory fitness and impaired fasting glucose and type 2 diabetes mellitus in men

BACKGROUND

Several studies show an inverse association between self-reported physical activity and type 2 diabetes. It is not known whether physical activity or cardiorespiratory fitness is associated with the onset of objectively determined impaired fasting glucose and type 2 diabetes.

OBJECTIVE

To determine whether cardiorespiratory fitness, an objective marker of physical activity, is associated with risk for impaired fasting glucose and type 2 diabetes.

DESIGN

Population-based prospective study.

SETTING

Preventive medicine clinic.

PATIENTS

8633 nondiabetic men (of whom 7511 did not have impaired fasting glucose) who were examined at least twice.

MEASUREMENTS

Cardiorespiratory fitness (determined by a maximal exercise test on a treadmill), fasting plasma glucose level, and other clinical and personal characteristics and incidence of impaired fasting glucose and type 2 diabetes.

RESULTS

During an average follow-up of 6 years, 149 patients developed type 2 diabetes and 593 patients developed impaired fasting glucose. After age, cigarette smoking, alcohol consumption, and parental diabetes were considered, men in the low-fitness group (the least fit 20% of the cohort) at baseline had a 1.9-fold risk (95% CI, 1.5- to 2.4-fold) for impaired fasting glucose and a 3.7-fold risk (CI, 2.4- to 5.8-fold) for diabetes compared with those in the high-fitness group (the most fit 40% of the cohort). The risk for impaired fasting glucose was elevated in older men and those with a higher body mass index. Age, body mass index, blood pressure, triglyceride level, and a history of parental diabetes were also directly related to risk for type 2 diabetes.

CONCLUSIONS

Low cardiorespiratory fitness was associated with increased risk for impaired fasting glucose and type 2 diabetes. A sedentary lifestyle may contribute to the progression from normal fasting glucose to impaired fasting glucose and diabetes. Risk for type 2 diabetes was elevated in older persons and those with higher body mass index, blood pressure, and triglyceride levels and a parental history of diabetes.

The alternation of optokinetic responses driven by moving stimuli in humans

When the two eyes were exposed dichoptically to two oppositely moving patterns, the alternating OKN was elicited, in which the eye movements tracked the two moving stimuli alternately. In the present experiment, two oppositely moving stimuli were periodically exchanged between the eyes, the results showed that the alternation of OKN direction was not affected by this exchange. It suggests that alternating OKN was not controlled by rivalry between the two eyes but between two perceived motion patterns.

The role of protein kinase C alpha and epsilon isozymes in DNA synthesis induced by muscarinic receptors in a glial cell line

Acetylcholine has been shown to induce proliferation of human astrocytoma cells by activating muscarinic receptors, particularly the m3 subtype. In the present study the role of protein kinase C in DNA synthesis induced by carbachol has been investigated. Carbachol-induced [methyl-3H]thymidine incorporation was inhibited by the protein kinase C inhibitors GF 109203X and staurosporine. However, carbachol-induced DNA synthesis was only partially reduced by protein kinase C down-regulation by phorbol 12-myristate 13-acetate (PMA), and maximal concentrations of carbachol and PMA had an additive effect on [methyl-3H]thymidine incorporation. Exposure for 24 h to maximally effective concentrations of carbachol did not induce down-regulation of protein kinase C alpha, and caused a small but significant down-regulation of protein kinase C epsilon; cells exposed for 24 h to carbachol were still able to respond with protein kinase C translocation to PMA stimulation. Carbachol caused a significant increase of phorbol ester binding, but did not stimulate protein kinase C alpha translocation, while it caused a short-lasting translocation of protein kinase C epsilon; however, protein kinase C epsilon translocation was not correlated with the time-course of carbachol-induced increase in [methyl-3H]thymidine incorporation. On the other hand, the time-course of translocation/down-regulation of protein kinase C alpha and protein kinase C epsilon induced by PMA was in good correlation with the time-course of PMA-induced [methyl-3H]thymidine incorporation. These results suggest that protein kinase C alpha may not be involved in DNA synthesis induced by muscarinic receptors stimulation in 132-1N1 astrocytoma cells, while protein kinase C epsilon appears to play a role in the initial exit from G0/G1 phase, though it cannot be considered the major determinant for sustained proliferation.

Effects of diabetes and level of glycemia on all-cause and cardiovascular mortality. The San Antonio Heart Study

OBJECTIVE

Although the level of hyperglycemia is clearly a risk factor for microvascular complications in diabetic patients, its role in macrovascular complications remains controversial. We followed 4,875 subjects (65% Mexican-American) for 7-8 years to investigate the effects of diabetes and hyperglycemia on all-cause and cardiovascular disease (CVD) mortality. These end points were also analyzed according to quartiles of baseline fasting plasma glucose among diabetic participants.

RESEARCH DESIGN AND METHODS

The Cox proportional hazards model was used to estimate the relative risks (RRs) for all-cause and CVD mortality.

RESULTS

Diabetes was significantly associated with increased all-cause mortality (RR [95% CI] = 2.1 [1.3-3.5] in men; 3.2 [1.9-5.4] in women) and increased CVD mortality (3.2 [1.4-7.1] in men; 8.5 [2.8-25.2] in women). Among diabetic subjects, those in quartile 4 had a 4.2-fold greater risk of all-cause mortality (P < 0.001) and a 4.7-fold greater risk of CVD mortality (P = 0.01) than those in quartiles 1 and 2 combined. After further adjustment for other potential risk factors, subjects in quartile 4 had a 4.9-fold greater risk of all-cause mortality and a 4.9-fold greater risk of CVD mortality than those in quartiles 1 and 2. In addition, hypertension, current smoking, and cholesterol > 6.2 mmol/l were significant predictors of CVD mortality using Cox models.

CONCLUSIONS

We conclude that diabetes is a predictor of both all-cause and CVD mortality in the general population and that both hyperglycemia and common CVD risk factors are important predictors of all-cause and CVD mortality in diabetic subjects.

[The enzymes activity of intestine grafts after combined small bowel/liver transplantation in rats]

OBJECTIVE

To study the alteration of the enzymes activity of intestine grafts after combined small bowel/liver transplantation in rats and the relations between their changes, functions and immune rejection.

METHOD

A kind of model of combined small bowel/liver transplantation (SLT) was established in SD closed colony rats. The enzymes activity of grafts were examined at regular postoperative intervals with histochemical methods.

RESULT

The enzymes activity of grafts disappeared eventually in isolated small bowel transplantation rats. Contrary, those in SLT rats were remained and recovered after operation.

CONCLUSION

The rejection in grafted intestine can be prevented or delayed in SLT rats. The examination of activity of enzymes and nerves in grafts may be used to monitor rejection and study function of grafts.

[Study on the effect of cyclic adenosine monophosphate on human erythrocyte membrane by FTIR and computer aided analysis]

The effect of cAMP on erythrocyte membrane proteins was studied by FITR, deconvolution and curvefitting. It was found that the change of cAMP's concentration affects the secondary structure of membrane proteins. The regulation of cAMP has a best concentration region, during which cAMP has the strongest effect.

Synthesis, solution structure and biological action of PACAP-related peptide

High quality PACAP-related peptide (PRP), a 29 amino-acid region of the PACAP precursor protein, has been synthesized in quantities sufficient for biological and structural studies. PRP has a distinct biological activity on the gallbladder that is similar to PACAP, but opposite to that of VIP and its related peptide, PHM. Its solution structure has been investigated by circular dichroism spectroscopy and 2D 1H nuclear magnetic resonance spectroscopy. In contrast to the poorly defined structure in aqueous solution alone, the limiting structure, under conditions that mimic a membrane-like environment, possesses stable secondary structure with a helical region between residues 3 and 20, that is terminated by the presence of glycine at residue 21 and is followed by a region of nascent helix. The similarities and differences in the structure of PRP, PACAP27 and GHRH(1-29) are made through comparison of their H alpha chemical shift data and differences in their biological activities assessed.

Changes in lipids associated with change in regular exercise in free-living men

OBJECTIVE

To investigate the relationship between regular exercise and plasma lipid profiles in free-living men.

METHODS

Seven hundred eighty men between the ages of 25 and 65 years were included in this study. The medical history, physical examination, and blood tests were obtained at baseline and 1 year later. At the end of the study, 430 (55.1%) men reported the same amount of regular exercise as a year earlier; 199 (25.5%) men reported an increased level, and 151 (19.4%) men reported a decreased level.

RESULTS

Compared to the group with same exercise, men who increased their level of regular exercise had a significant increase in high-density lipoprotein cholesterol (HDLC) (mean 4.76 versus 2.83 mg/dL, p < 0.005) and significant decreases in the ratio of total cholesterol/HDLC (mean -0.72 versus -0.42, p < 0.001) and triglycerides (mean -18.2 versus -6.27 mg/dL, p < 0.001). The changes in lipid profiles appeared to have a dose-response relationship from the increased exercise, same exercise, to decreased exercise groups. Overweight and normal-weight men had a similar tendency to improve their lipid profiles by exercise. The improvement in plasma lipid profile associated with increased regular exercise persisted after controlling for potential confounders.

CONCLUSIONS

The results indicate that the relationship between physical activity and favorable lipid profiles exists in men with mild-to-moderate physical activity.

[Prophylactic effects of magnesium sulfate and ligustrazin on the hypoxic-ischemic brain damage in neonatal rats]

OBJECTIVE

A model in neonatal rats was established to study pathophysiology of perinatal hypoxic-ischemic brain damage.

METHODS

7-9 day old Wistar rats were subjected to unilateral carotied artery ligation followed by hypoxic state for 3 hours (10% O2 + 90% N2, at 37 degrees C). Magnesium sulfate (0.5 mg/gBW) and ligustrazin (0.1 mg/gBW) was separately given a 30 min before hypoxia. Superoxide dismutase (SOD) and malonic dialdehyde (MDA) in the cerebral cortex and serum MDA were measured immediately after hypoxia. Neuropathologic examination was made in 4 weeks after hypoxia.

RESULTS

It was found that SOD and MDA in the cerebral cortex and serum MDA in the hypoxicischemic group were significantly increased in comparision with the normal control group (P < 0.01), and that all these parameters either in the magnesium sulfate group or in the ligustrazin group were lower than in the hypoxic-ischemic group (P < 0.05). The hypoxic-ischemic group showed that there were neuronal degenerations in the gray matter, hippocampus and cerebellum which were reduced in the two treatment groups.

CONCLUSION

Our results indicate that oxide free radical formation is one of the pathogenic factors of perinatal hypoxic-ischemic brain damage and magnesium sulfate and ligustrazin reduce hypoxicischemic brain damage due to indirect anti-oxidation.

High responsiveness of cytosolic free calcium concentration to angiotensin II in cultured pulmonary arterial myocytes from pulmonary hypertensive rats

Pulmonary arterial myocytes were cultured from normotensive and pulmonary hypertensive rats. Microfluorimetry of Ca2+ signals in fluo-3-loaded single myocytes at day 7 of culture was performed by a laser-scanned confocal imaging system. The resting level of cytoplasmic Ca2+ concentration ([Ca2+]i) in vascular myocytes obtained from hypertensive rats was higher than that in cultured myocytes obtained from normotensive rats. Angiotensin II elevated [Ca2+]i in the vascular myocytes cultured from both normotensive and hypertensive rats. However, a rise of [Ca2+]i induced by angiotensin II in the vascular myocytes obtained from pulmonary hypertensive rats was higher than that obtained from normotensive rats. On the other hand, the response of [Ca2+]i to A23187 did not differ between the vascular myocytes cultured from normotensive and hypertensive rats. The present results suggest that the resting and angiotensin II-responsive levels of [Ca2+]i in pulmonary arterial myocytes cultured from pulmonary hypertensive rats are higher than those cultured from normotensive rats.

Responsiveness of cytosolic free calcium concentration in cultured rat pulmonary arterial smooth muscle cells: confocal microscopic measurement

Rat pulmonary arterial smooth muscle cells were primarily cultured. alpha-actins in pulmonary arterial smooth muscle cells at day 7 of culture were observed by an immunofluorescence staining method using anti-alpha-actin antibody. Microfluorimetry of Ca2+ signals in fluo-3-loaded single smooth cell at day 7 of culture was performed by a laser-scanned confocal imaging system. The effects of several kinds of Ca(2+)-mobilizing drugs on cytoplasmic Ca2+ concentration ([Ca2+]i) were examined. KCl, a depolarizing agent, and norepinephrine, an alpha-adrenergic agonist, equally increased [Ca2+]i. Angiotensin II, a receptor agonist, and caffeine, a Ca(2+)-induced Ca2+ releaser, elevated [Ca2+]i in the same manner but was more potent than KCl and norepinephrine. Br-A23187, a Ca2+ ionophore, most potently increased [Ca2+]i. The present results suggest that drug receptors on plasma membrane, Ca2+ entry pathways and Ca(2+)-releasing mechanisms act normally, and that our cultured pulmonary arterial smooth muscle cells may be a good model for the study on the essential role of Ca2+ in vasoconstriction.

[Regeneration of functionally active rat brain muscarinic receptor in vitro after inhibition with methylmercury chloride]

The effect of methylmercury on muscarinic receptors and the regeneration of functionally active muscarinic receptor in vitro by antagonists were investigated. The result showed that methylmercury chloride (MMC) inhibited the binding of [3H] QNB to muscarinic receptor of rat brain-lysed synaptosomes, with IC50 values of 4.18 mmol/L. Regeneration of functionally active rat brain muscarinic receptors after inhibition with methylmercury was achieved by 2,3-dimercapto-1-propanesulfonc acid, Na salt (DMPS) dithiothreitol (DTT), glutathione (GSH) and Cysteine. Blocking the sulfhydryl groups is suggested to be the molecular mechanism of inhibition of brain muscarinic receptors by methylmercury. Our results provide evidence that thiols chelate out mercuric cations that tightly bound to sulfhydryl groups in muscarinic receptor binding sites and regenerate [3H] QNB binding activity.