The study of the relationship between the activity of phospholipase A2 and acute hypoxic pulmonary arterial pressure

The role of phospholipase A2 (PLA2) and related inflammatory mediators in the mechanism of hypoxic pulmonary arterial hypertension was studied. Thirty Sprague-Dawley rats were equally divided into three groups at random: group A was the normal control group; group B was given 10% oxygen ventilation; group C was given 10% oxygen ventilation too and, at the same time, dexamethasone was injected into the external jugular vein. The pulmonary arterial pressure (PAP) was measured by inserting a microcatheter into pulmonary artery. After 30 minutes of hypoxia, the activity of PLA2, platelet activating factor (PAF), prostaglandin E2 (PGE2) and tromboxane B2 (TXB2) were measured in blood and lung tissue. After hypoxia, the mean pulmonary arterial pressure (mPAP), the PLA2 activity, PGE2, TXB2 and PAF in blood and lung tissue of group B were significantly higher than in group A; in group C the same parameters were lower than in group B. In hypoxia, a positive correlations was found between the PLA2 activity and mPAP, PAF, PGE2, TXB2 respectively; positive correlations were also found between PAF, PGE2, TXB2 and mPAP. PLA2 induced release of inflammation mediators, plays an important role in the mechanism of the acute hypoxic pulmonary arterial hypertension.

DNA topoisomerase II as the primary cellular target for salvicine in Saccharomyces cerevisiae

AIM

To identify whether DNA topoisomerase II (Topo II) is the primary cellular target of salvicine in Saccharomyces cerevisiae (S cerevisiae) and the action mode of salvicine.

METHODS

The catalytic activity of Topo II was determined by Topo II mediated supercoiled pBR322 relaxation. The effects of salvicine on the growth of four strains of S cerevisiae were assessed by clone forming assay.

RESULTS

Salvicine inhibited Topo II mediated supercoiled pBR322 relaxation in cell-free system. Cytotoxicities of salvicine to parent (JN394) and TOP1 deleted (JN394top1-) yeast cells were at the same level, suggesting Topo I might not be the cellular target of salvicine. Salvicine displayed high activity against JN394t2-1 cells at 25 degrees C, while no growth inhibition was observed at 30 degrees C in the concentration range of interest. Furthermore, JN394t2-5 cells which expressed top2-5 mutant allele were highly resistant to salvicine and etoposide (VP16).

CONCLUSION

Topo II was the primary cellular target of salvicine in vivo and salvicine killed yeast cells mainly by trapping the DNA-Topo II cleavage complex. Salvicine and VP16 might share some similar action locus on Topo II.

[Study on the relations between HLA-DRB 1 alleles and Helicobacter pylori infection]

OBJECTIVE

In order to study the relation between human leukocyte antigen (HLA) DRB1 alleles and Helicobacter pylori (Hp) infection.

METHODS

Hp-IgG antibody from 46 gastric cancer (GC), 75 esophageal cancer and 100 population-based controls were identified by Hp-IgG quantitative enzyme immunoassay. Biotest HLA-DRB enzyme linked probe hybridization assay kit (low resolution) was used to identify DRB1 alleles.

RESULTS

(1) Frequency of DRB1 * 08 was significantly higher in Hp-IgG positive group than in Hp-IgG negative group (13.1% vs 4.4%, chi(2) = 11.14, P < 0.001). Frequency of DRB1 * 12 was significantly lower in Hp-IgG positive group than in Hp-IgG negatives (5.4% vs 11.3%, chi(2) = 4.49, P < 0.05). (2) Frequency of DRB1 * 02 in GC was significantly higher than that of controls. Frequency of DRB1 * 07 in GC was significantly lower than that of controls. However, neither the frequency of DRB1 * 02 between Hp-IgG positive and Hp-IgG negative groups nor the frequency of DRB1 * 07 between Hp-IgG positive and Hp-IgG negative groups showed significant differences in GC and controls.

CONCLUSIONS

(1) HLA-DRB1 * 08 might serve a genetic risk factor for Hp infection while DRB1 * 12 might play a role of protecting effect against Hp infection. (2) DRB1 * 02 might be a genetic risk factor for GC while DRB1 * 07 might play a role of protecting effect against GC. However, the relations between DRB1 * 02, DRB1 * 07 and GC were not associated with Hp infection.

Abstract P6-09-19: Breast density change at 6 months is associated with change at 12 months as measured by fat-water decomposition MRI in women on tamoxifen

Objective: Tamoxifen (TAM) lowers breast cancer recurrence by 40-50% with evidence of individual variability in responsiveness. A ≥10% decrease in mammography-determined breast density (BD) after 12–18 months of TAM use has been associated with clinical benefit. Early determination of changes in BD may offer a strategy to tailor hormone therapy in non-responders; for responders, it may encourage adherence. Fat-water decomposition MRI (FWD-MRI) is an accurate and fast (&lt; 5 minutes) method for measuring BD without ionizing radiation or contrast agent. Here, we examined whether change in FWD-MRI-derived BD predicts decrease in BD at earlier time points than observable with a 12-month measure of BD.

Methods: The study population included a subset of 44 pre- and post-menopausal women receiving TAM for treatment of early-stage breast cancer or prevention who were enrolled in a randomized, placebo-controlled trial of diindolylmethane. Eligibility for this analysis included participants with FWD-MRI scans at baseline, 6 and 12 months. Median time on TAM at baseline was 13 months (IQR, 5–26 months). All MRI images were acquired on a 1.5T GE Signa NV-CV/i scanner. Automated breast segmentation was performed using MATLAB software and validated against manual ROI drawings. MRI-based BD was calculated as the ratio of breast voxels with &lt;80% apparent fat fraction (Fra80) over the entire breast, a measure previously shown by our group to be highly correlated with mammography-derived BD. For 40 participants, the unaffected, contralateral breast was analyzed. For 4 patients with two unaffected breasts, BD data from the left breast were analyzed. Change in BD was conservatively defined as &gt; 2 times the test-retest variability of Fra80 (0.032). McNemar's test was used to test the association between change from baseline to 6 months and change from baseline to 12 months.

Results and Discussion: At 12 months, 15 (34%) participants had a decrease in BD, whereas 29 (66%) remained unchanged or increased. Of these 29, 28 also had no decrease at 6 months (specificity = 97%), and 9 of the 15 women who showed a decrease at 12 months had a decrease at 6 months (sensitivity = 60%; McNemar's test, P = 0.06). Conversely, for those women with a measured decrease in BD from baseline to 6 months, 9 of 10 had a measured decrease at 12 months. A study limitation is inclusion of participants on TAM for varying duration as the greatest change in BD likely would have occurred earlier. Ongoing efforts will focus on FWD-MRI for measures of change in BD in patients initiating TAM.

Conclusion: Use of the specified cut point would fail to detect a decrease in BD at 12 months in 40% of women. However, a decrease in BD from baseline to 6 months was highly associated with decrease from baseline to 12 months and in some women may be useful as an early biomarker of effect. Ongoing effort is needed to determine the impact of factors such as baseline BD, menopausal status, and time on TAM in misclassification of BD change using the 6-month measure.

Acknowledgement: NIH grants CA149417, CA161534.Objective: Tamoxifen (TAM) lowers breast cancer recurrence by 40-50% with evidence of individual variability in responsiveness. A ≥10% decrease in mammography-determined breast density (BD) after 12–18 months of TAM use has been associated with clinical benefit. Early determination of changes in BD may offer a strategy to tailor hormone therapy in non-responders; for responders, it may encourage adherence. Fat-water decomposition MRI (FWD-MRI) is an accurate and fast (&lt; 5 minutes) method for measuring BD without ionizing radiation or contrast agent. Here, we examined whether change in FWD-MRI-derived BD predicts decrease in BD at earlier time points than observable with a 12-month measure of BD.

Methods: The study population included a subset of 44 pre- and post-menopausal women receiving TAM for treatment of early-stage breast cancer or prevention who were enrolled in a randomized, placebo-controlled trial of diindolylmethane. Eligibility for this analysis included participants with FWD-MRI scans at baseline, 6 and 12 months. Median time on TAM at baseline was 13 months (IQR, 5–26 months). All MRI images were acquired on a 1.5T GE Signa NV-CV/i scanner. Automated breast segmentation was performed using MATLAB software and validated against manual ROI drawings. MRI-based BD was calculated as the ratio of breast voxels with &lt;80% apparent fat fraction (Fra80) over the entire breast, a measure previously shown by our group to be highly correlated with mammography-derived BD. For 40 participants, the unaffected, contralateral breast was analyzed. For 4 patients with two unaffected breasts, BD data from the left breast were analyzed. Change in BD was conservatively defined as &gt; 2 times the test-retest variability of Fra80 (0.032). McNemar's test was used to test the association between change from baseline to 6 months and change from baseline to 12 months.

Results and Discussion: At 12 months, 15 (34%) participants had a decrease in BD, whereas 29 (66%) remained unchanged or increased. Of these 29, 28 also had no decrease at 6 months (specificity = 97%), and 9 of the 15 women who showed a decrease at 12 months had a decrease at 6 months (sensitivity = 60%; McNemar's test, P = 0.06). Conversely, for those women with a measured decrease in BD from baseline to 6 months, 9 of 10 had a measured decrease at 12 months. A study limitation is inclusion of participants on TAM for varying duration as the greatest change in BD likely would have occurred earlier. Ongoing efforts will focus on FWD-MRI for measures of change in BD in patients initiating TAM.

Conclusion: Use of the specified cut point would fail to detect a decrease in BD at 12 months in 40% of women. However, a decrease in BD from baseline to 6 months was highly associated with decrease from baseline to 12 months and in some women may be useful as an early biomarker of effect. Ongoing effort is needed to determine the impact of factors such as baseline BD, menopausal status, and time on TAM in misclassification of BD change using the 6-month measure.

Acknowledgement: NIH grants CA149417, CA161534.

Citation Format: Ding J, Thompson PA, Wertheim BC, Roe DJ, Marron MT, Altbach MI, Galons J-P, Wang F, Thomson CA, Huang C, Stopeck A. Breast density change at 6 months is associated with change at 12 months as measured by fat-water decomposition MRI in women on tamoxifen [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P6-09-19.

Abstract P3-02-03: Accurate and reliable automated breast density measurements with no ionizing radiation using fat-water decomposition MRI

Objective Breast density(BD) is a measure of the distribution of variable tissue types within the breast and higher BD has been shown to positively correlate with breast cancer risk. As such, the accurate measurement of BD has become a priority for risk assessment and for evaluating the effects of prevention strategies aimed at reducing BD. Mammography(MG) is the most common method of BD determination but is limited by the exposure to ionizing radiation, particularly for studies requiring repeated measures. BD derived from fat-water decomposition magnetic resonance imaging(FWMRI-BD) has been proposed as an alternative, safe, and quantitative method for BD. To optimize its use, we developed a new FWMRI-BD that is automated, more accurate and reliable. In this study, we compare our automated method to digital MG and a previous reported algorithm for MRI derived BD.

Methods From a completed prevention trial, 42 pre- and post-menopausal patients receiving tamoxifen therapy for early stage breast cancer or as primary chemoprevention were identified. Patients had undergone prior digital MG within 6 months from the date of MRI scan and MG-BD was calculated using a well-established method(Cumulus). MRI scans were performed on a 1.5T GE Signa NV-CV/i scanner using an axial radial IDEAL-GRASE sequence to generate quantitative fat fraction maps of the entire breast. Total acquisition time was &lt; 5 min and automated breast segmentation was applied to all scans. Only the contralateral, unaffected breast was analyzed. Pearson correlation analysis compared BD as measured by MG(range 0-100%) and FWMRI based methods. BD by FWMRI was initially calculated as the ratio of breast voxels with&lt;80% apparent fat fraction(Fra80). Fra80 had been previously shown by our group to correlate with MG-BD(Spearman ρ=0.86, p&lt;0.001). Here, BD was calculated using a new algorithm(FraG+W) that accounts for the total amount of fibroglandular tissue and water content in the breast after correction for fat-water signal intensity bias and fat-water signal shine-through. Reliability of FWMRI measurements was tested in 24 repeated scans from 9 patients and evaluated using intra-class correlation(ICC) analysis.

Results Table 1 shows the correlation and reliability analysis results between MG-BD and FWMRI-BD. Both FWMRI-BD measures(Fra80 and FraG+W) were strongly correlated with MG-BD. More importantly, they exhibit superior test-retest reliability(ICC&gt;0.98) compared to MG-BD values from the literature(reported ICC range 0.91-0.95). FraG+W showed improvement over Fra80 in all measures tested including correlation to MG-BD, dynamic range, standard errors and ICC.

Table 1. Accuracy and Reliability of the FWMRI-BD measuresFWMRI-BDFra80FraG+WPearson correlation coefficient* with MG-BDR=0.86R=0.94Test-retest reliabilitystandard error0.02300.0134dynamic range0.0902 – 0.65370.0736 – 0.6588standard error/ dynamic range4.1%2.3%ICC [95% confidence interval]0.985 [0.966,0.993]0.990 [0.976,0.995]* All P-values &lt; 1e-10

Conclusion The refined and automated FWMRI-BD that quantifies the entire fibroglandular and water content of the breast(FraG+W) strongly correlates with MG-BD and is more accurate and reliable than previous FWMRI-BD method.

Acknowledgement NIH grants CA149417, CA161534.

Citation Format: Ding J, Thompson PA, Gao Y, Marron MT, Wertheim BC, Altbach MI, Galons J-P, Roe DJ, Wang F, Maskarinec G, Thomson CA, Stopeck A, Huang C. Accurate and reliable automated breast density measurements with no ionizing radiation using fat-water decomposition MRI [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-02-03.

Establishment of a subcutaneous model of the human extrahepatic bile duct carcinoma in nude mice via transplantation of histologically intact tumor tissue

The purpose of the study was to establish the subcutaneous model of human extrahepatic bile duct carcinoma in nude mice so as to provide a suitable model for the study of extrahepatic bile duct carcinoma. Surgical specimens of the patient with extrahepatic bile duct carcinoma were transplanted into the subcutaneous layer of nude mice. Growth curve of transplanted tumors was drawn and its morphological and biological characteristics, as well as choromosome were observed. A well differentiated mucinous adenocarcinoma model of human bile duct carcinoma in nude mice, designated as HBDCM1-ZSH (Human Bile Duct Carcinoma Model No. 1 established by Zhong Shan Hospital in April, 2001), was established via subcutaneous transplantation of the surgically resected tumor from a 56-year-old Chinese man. HBDCM1-ZSH has been maintained for 13 passages and exhibited 98.1% transplantability. Mean latent periods were 26 days. Transplanted tumors exhibited the characteristics of the original tumor in morphology and biology. Chromosomal analysis revealed numerical abnormalities ranging from 67 to 84. HBDCM1-ZSH expressed carcinoembryonic antigen (CEA), carbohydrate antigen (CA)19-9, cytokeratin (CK7, CK19, CK20), PCNA, AB and PAS. In conclusion, HBDCM1-ZSH is similar to human extrahepatic bile duct carcinoma and provides an applicable animal model for research on extrahepatic bile duct carcinoma.

[Peripheral nerve injury in LAMA2-related congenital muscular dystrophy patients]

Objective: To explore the injury pattern and features of peripheral nerve in congenital muscular dystrophy patients caused by LAMA2 gene mutation. Method: Seventeen patients genetically or molecular pathologically diagnosed as LAMA2-related congenital muscular dystrophy were recruited in Peking University First Hospital between 2002 and 2015. All the patients received nerve conduction velocity (NCV) and needle electromyography tests. Clinical and laboratory examination data of the patients was retrospectively analyzed. The correlation between the NCV and disease course was determined by Pearson correlation analysis. Additionally, one patient underwent a sural nerve biopsy. Result: Among these 17 identified patients (13 male and 4 female), all of them were diagnosed as congenital muscular dystrophy, and all of them underwent electrophysiological examination at ages between 1 month to 6 years. Electromyogram indicated seventeen patients of myogenic damage, of whom 10 cases were complicated with reduced NCV. Twenty-six of 95 analyzed nerves showed NCV slower than the normal average of contemporary in 17%-47%. Correlation analysis between NCV and the disease course indicated that NCV of median nerves, ulnar nerves, tibial nerves and common peroneal nerves were negatively associated with the disease course (r=-0.737, -0.771, -0.540 and -0.682, respectively; all P<0.05). Sural nerve biopsy revealed peripheral neuropathy changes of myelin. Conclusion: There is peripheral nerve injury in LAMA2-related muscular dystrophy patients. It mainly manifests as demyelinating lesions. Moreover, the NCV of peripheral nerve will decrease with the increase of the course of the disease.

[Association between fatty liver and type 2 diabetes in the baseline population of Jinchang Cohort]

Objective: To explore the association between fatty liver and type 2 diabetes mellitus (T2DM) in the baseline-population of Jinchang cohort study. Methods: Data from all the participants involved in the baseline-population of Jinchang cohort study was used, to compare the risks of T2DM in fatty liver and non fatty liver groups and to explore the interaction between family history or fatty liver of diabetes and the prevalence of T2DM. Results: Among all the 46 861 participants, 10 574 were diagnosed as having fatty liver (22.56%), with the standardized rate as 20.66%. Another 3 818 participants were diagnosed as having T2DM (8.15%) with standardized rate as 6.90%. The prevalence of T2DM increased in parallel with the increase of age (trend χ(2)=2 833.671, trend P<0.001). The prevalence of T2DM in the fatty liver group was significantly higher than that in the non-fatty liver group, both in men or women and in the overall population. Compared with the group of non-fatty liver, the risks of T2DM in fatty liver group were seen 1.78 times higher in males, 2.33 times in women and 2.10 times in the overall population, after adjustment for factors as age, levels of education, smoking, drinking, physical exercise, BMI, family history of diabetes and some metabolic indicators (pressure, TC, TG, uric acid, ALT, AST, gamma-glutamyl transferase). Date from the interaction model showed that fatty liver and family history of diabetes present a positive additive interaction on T2DM (RERI=1.18, 95%CI: 0.59-1.78; AP=0.24, 95%CI: 0.14-0.34; S=1.43, 95%CI: 1.21-1.69). Conclusions: Fatty liver could significantly increase the risk of T2DM and a positive additive interaction was also observed between fatty liver and family history of diabetes on T2DM. It was important to strengthen the prevention program on T2DM, in order to effectively control the development of fatty liver.

A survey on parasites in wild rodents in Xiji County, a northwestern part of China

Rodents act as an indicator for evaluation of environment contaminations and public health risks caused by parasites. A survey of parasites in wild rodents was conducted in 14 villages in Xijin County, where alveolar echinococcosis by Echinococcus multilocularis is epidemic. In total, 72 rodents including 25 mice, 16 Citellus dauricus (Daurian ground squirrel), 12 squirrels and 19 mole rat (Myospalax fontanieri) were captured. Infections (2.8%) of Taenia taeniaeformis, which is transmitted mainly between mice and cats, were found in mice in Wangping (WP) and Miaoping (MP) villages, but other cestodes' infections were not observed. WP and MP isolates were principally similar in morphology but, unlike WP isolate, MP isolate had no hooks on the scolex. Using 18S rRNA as a biomarker, the phylogenetic analysis showed that WP and MP isolates grouped together with European and Asian isolates and formed a separate cluster. These results highlights the prevalence of T. taeniaeformis in cats or/and dogs and a risk of opportunistic infections in human populations.

Erratum to: Association between Modifiable Risk Factors and Levels of Blood-Based Biomarkers of Alzheimer's and Related Dementias in the Look AHEAD Cohort

[This corrects the article DOI: 10.14283/jarlife.2024.1.].

Reciprocal interactions between protein kinase C and components of the NADPH oxidase complex may regulate superoxide production by neutrophils stimulated with a phorbol ester

The 47-kDa subunit of the NADPH oxidase system (p47-phox) of neutrophils undergoes an association with proteins in the Triton X-100-insoluble fraction upon stimulation of the cells with 4 beta-phorbol 12-myristate 13-acetate. This fraction contains the assembled oxidase that catalyzes the generation of superoxide by stimulated cells. In this paper, we report that the addition of an inhibitor of protein kinases (1-(5-isoquinolinylsulfonyl-2-methylpiperazine) to neutrophils that are already stimulated results in the dissociation of p47-phox from this fraction. Antagonists of type 1 and 2A protein phosphatases (calyculin A, okadaic acid) prevented this phenomenon. In contrast, norokadanone, an inactive analog of okadaic acid, did not affect this response. These observations are correlated with previous studies on the phosphorylation of p47-phox and superoxide release. In addition, we show that protein kinase C (PKC) also undergoes an extensive redistribution to the Triton X-100-insoluble fraction in 4 beta-phorbol 12-myristate 13-acetate-stimulated cells, the extent of which is diminished significantly in neutrophils from chronic granulomatous disease patients who lack either p47-phox or cytochrome b558. These studies strongly indicate that PKC and type 1 and/or 2A protein phosphatases are involved in a continuous phosphorylation reaction that maintains the oxidase in the assembled/active state. Moreover, components of the oxidase may target and facilitate the translocation of PKC to a cellular site in close apposition to the oxidase.

Farnesyl-L-cysteine analogs can inhibit or initiate superoxide release by human neutrophils

A series of farnesylcysteine analogs was studied with respect to their abilities to interfere with fMet-Leu-Phe (fMLP)-stimulated superoxide (O2-.) release by human neutrophils. Simple acyl derivatives of farnesyl-L-cysteine, such as the N-acetyl (L-AFC) and N-isobutyryl derivatives (L-iBFC), which are substrates for the isoprenylated protein methyltransferase, can block O2-. release. The N-butyryl analog (L-BFC), which is an isomer of L-iBFC and also a substrate for the methyltransferase, does not inhibit O2-. release but actually stimulates it in the absence of fMLP. Other analogs, including the N-pivaloyl derivative, which has been found to be neither a substrate nor an inhibitor of methyltransferase, also stimulate very large quantities of O2-. production. The stimulatory effects of these derivatives are saturable and exquisitively sensitive to small structural changes in the analogs. The signal transduction pathway(s) utilized by pivaloyl derivatives for triggering O2-. generation is very similar to that employed by fMLP. These data make it clear that farnesyl-L-cysteine analogs do not produce their pharmacological effects in neutrophils via methyltransferase blockade. This could be further demonstrated by showing that sinefungin and S-adenosylhomocysteine, both powerful and general methyltransferase inhibitors which bind at the S-adenosylmethionine site, had no effect in preventing the increased oxygen consumption associated with O2-. production in permeabilized neutrophils. These studies reveal that farnesyl-L-cysteine analogs interact with a hitherto undefined target in neutrophils that may be exploited for inhibiting or stimulating the inflammatory or antimicrobial responses of these cells.

Effects of antagonists of protein phosphatases on superoxide release by neutrophils

Neutrophils stimulated with 4 beta-phorbol 12-myristate 13-acetate (PMA) release large quantities of superoxide (O2-) and exhibit phosphorylation of two proteins with molecular masses of 47(p47) and 49 kDa (p49). Addition of inhibitors of protein kinases (e.g. 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7)) to these cells after stimulation with PMA results in the loss of 32P from these proteins and a rapid cessation of O2- release (e.g. Heyworth, P. G., and Badwey, J. A. (1990) Biochim. Biophys. Acta 1052, 299-305). In this paper we report that antagonists of type 1 and 2A protein phosphatases (okadaic acid, calyculin A) prevented both the loss of 32P from p47 and the termination of O2- release in stimulated neutrophils treated with H-7. Calyculin A also caused a remarkable hyperphosphorylation of a number of proteins in neutrophils and increased O2- release from these cells in response to a suboptimal amount of PMA. Enzymes present in both the soluble and particulate fractions of neutrophils catalyzed the near complete dephosphorylation of 32P-labeled p47 and p49 bound to Immobilon-P membranes. Dephosphorylation of these blotted phosphoproteins occurred at physiological rates and was inhibited by okadaic acid and calyculin A. These data strongly suggest that p47 undergoes a continual cycle of phosphorylation and dephosphorylation throughout the period of O2- release when PMA is the stimulus. Moreover, we show that antagonists of type 1 and 2A protein phosphatases block dephosphorylation of p47 both in vivo and in vitro, indicating that these enzymes may modulate O2- release under certain circumstances.

Atrial natriuretic factor and renin synthesized in cultured aortic smooth muscle cells of rats

This study was designed to determine whether or not atrial natriuretic factor (ANF) is present in the vascular walls and to observe the differences in ANF between control (WKY) and stroke-prone spontaneously hypertensive rats (SHRsp). It was found that ANF is indeed present in the vascular wall of the distal aorta. HPLC analysis of the extracts from cultured aortic smooth muscle cells (ASMC) and medium revealed that intracellular ANF was mainly in the form of ANF(1-126), at levels of 0.82 +/- 0.03 (SHRsp) and 1.04 +/- 0.10 ng/10(6) cells (WKY), while the major form in the medium was ANF(99-126), at levels of 0.40 +/- 0.06 and 0.60 +/- 0.06 ng/10(6) cells, respectively. Both forms were present in smaller amounts in SHRsp than in WKY rats. On the contrary, both renin activity and angiotensin I concentrations in SHRsp cells were significantly higher than those in the WKY controls. In addition, immunocytochemistry showed positive ANF staining in cultured ASMC of both strains. The results suggest that ANF can be synthesized and secreted by cultured ASMC from rats.