Biomedical subjects

Y H Hwang

Publications and source records attributed to Y H Hwang.

At least 19 recordsLinked to original sources

PubMed2006

Biofeedback therapy for rectal intussusception.

BACKGROUND: Surgery for isolated internal rectal intussusception is controversial due to high morbidity. Therefore, there is interest in other forms of treatment that are safe and effective. The aim of this study was to determine outcome and identify predictors for success of biofeedback therapy in patients with rectal intussusception. METHODS: We retrospectively evaluated the results of electromyography (EMG)-based biofeedback in 34 patients with rectal intussusception without any other major pelvic floor or colonic physiologic disorder. RESULTS: A total of 34 patients (7 men) had undergone at least 2 biofeedback sessions. The patients had a mean age of 68.5 years (SD=11.4 years). In the 27 patients with constipation, the frequency of weekly spontaneous bowel movements (mean+/-SD) was 2.0+/-6.8 before and 4.1+/-4.6 after biofeedback (p<0.05). The frequency of weekly assisted bowel movements decreased from 3.8+/-3.5 before to 1.5+/-2.2 after therapy (p<0.005). The number of patients who experienced incomplete evacuation decreased from 17 (63%) to 9 (33%) (p<0.05). Thirty-three percent of patients had complete resolution of the symptoms, 19% had partial improvement, and 48% had no improvement. Patients with constipation lasting less than nine years had a 78% success rate vs. 13% in patients who were constipated more than 9 years (p<0.01). In seven patients with incontinence, the frequency of daily incontinence episodes decreased from 1.0+/-0.7 before to 0.07+/-0.06 after biofeedback (p<0.05). The fecal incontinence score decreased from 13.1+/-4.2 before to 4.6+/-3.6 after treatment (p<0.005). Two patients (29%) were completely continent following biofeedback, 2 had partial improvement, and 3 (43%) had no significant improvement. There was no mortality in either group. CONCLUSIONS: Biofeedback is a safe and effective treatment option for constipation and fecal incontinence due to rectal intussusception in patients who are willing to complete the course of treatment. Long-standing constipation is less effectively cured by biofeedback.

Aged↗

PubMed2006

Fatty acids, inhibitors for the DNA binding of c-Myc/Max dimer, suppress proliferation and induce apoptosis of differentiated HL-60 human leukemia cell.

c-Myc is instrumental in the progression of Burkitt's lymphoma including HL-60 human leukemia cells. We tested fatty acids for their inhibitory effect on the DNA binding of c-Myc/Max dimeric proteins of human origin, prepared as recombinant proteins encompassing DNA binding (basic) and dimerization (HLHZip) domain, and found that those suppress proliferation and induce apoptosis of DMSO-differentiated HL-60 cells. The analyzed IC50 values of myristic acid, stearic acid, gamma-linolenic acid, linoleic acid, linolenic acid and arachidonic acid by EMSA were 97(+/-3), 2.2(+/-1.2), 55(+/-5), 32(+/-2), 62(+/-12), 22(+/-2)microM for DNA binding of recombinant c-Myc/Max, respectively. According to the results shown by XTT assay, their influence on proliferation was quite different from the rank order of IC50. Whereas the degree of influence of the unsaturated fatty acids on the proliferation of DMSO-differentiated HL-60 cells was similar, the influence of saturated fatty acids, stearic acid in particular, was very weak at same concentrations. In addition, we confirmed that these fatty acids have no influence on the expression of c-Myc in DMSO-differentiated HL-60 cells. Our experiments demonstrated that the inhibitors for the DNA binding of c-Myc/Max contribute to the downregulation of Myc-dependent proliferation and to the inducement of apoptosis, and serve as an exploration of potent new inhibitors.

Apoptosis↗

PubMed2006

PKD2 gene mutation analysis in Korean autosomal dominant polycystic kidney disease patients using two-dimensional gene scanning.

Autosomal dominant polycystic kidney disease (ADPKD) is genetically heterogeneous and is caused by mutations in the PKD1 or PKD2 genes. ADPKD caused by PKD2 mutations is characterized by a longer survival and a later onset of end-stage renal disease than ADPKD caused by PKD1 mutations. PKD2 encodes a 2.9-kb messenger RNA and is derived from 15 exons. Two-dimensional gene scanning (TDGS) is more efficient in detecting mutations in genes such as PKD2 because it can scan the whole coding regions simultaneously. In order to determine the prevalence of Korean PKD2 patients, all the coding sequences of PKD2 were screened using TDGS and direct sequencing in 46 randomly selected ADPKD patients (group 1). Another 45 ADPKD patients (group 2), who were presumed to be PKD2 patients, were screened in order to identify the type of mutation in the Korean PKD2 patients. Eight novel different mutations and three known mutations in the PKD2 gene were detected in 17 patients: 6 patients (13.0%) in group 1 and 11 patients (24.4%) in group 2. Considering the sensitivity of TDGS, the prevalence of PKD2 in Korean population might be greater than 18.6%. Both known and novel mutations were identified by TDGS in Korean PKD2 patients. Overall, these results showed that TDGS might be useful for diagnosing PKD2.

Chromosome Mapping↗

PubMed2003

Epidemiology of otitis media in Chinese children.

From May to July 2001, 3013 Chinese children, aged 3-6 years old, from 19 kindergartens in Kaohsiung were examined for the prevalence of otitis media. A senior paediatric otolaryngologist performed examinations. Tympanometric and otoscopic records were combined for assessment of middle ear status. The prevalence rate of otitis media was 9.82% for all children, 5.24% for middle ear effusion and 5.34% for retracted tympanic membrane. The prevalence rates of otitis media in different age groups were as follows: 11.3% for 3-year-olds, 12.4% for 4-year-olds, 11.8% for 5-year-olds, and 6.1% for 6-year-olds. Considering the genetic factors and the previous history of otitis media, there was a significant difference between the normal group and the sick group.

Acoustic Impedance Tests↗

PubMed2003

No association of the TGF-beta1 gene polymorphisms with the renal progression in autosomal dominant polycystic kidney disease (ADPKD) patients.

BACKGROUND: Two genetic loci, PKD I and PKD2, have been identified as being responsible for ADPKD, and PKD1 is known to be associated with a poor prognosis. However, the presence of an intrafamilial study clinical diversity suggests that there are disease-modifying loci. Because the mechanism ofthe renal failure in ADPKD includes a cystic growth and tubulointerstitial atrophy and fibrosis, we studied the associations between 2 polymorphisms in the TGF-beta1 gene, which are known to be associated with chronic tubulointerstitial inflammation, and ADPKD progression in Korean patients. PATIENTS AND METHODS: One hundred and twenty-five individuals who had ADPKD and 47 normal control subjects were genotyped by PCR-RFLP, the T869C (Leu10Pro) variant of TGF-beta gene leader sequence was discriminated with MspA1I and the G915C (Arg25Pro) variants with Bg1I. Statistical significances were determined using the Chi-square test. RESULTS: The distribution of the alleles for the TGF beta1 Leu10Pro polymorphism in ADPKD was: T 54%, C 46%, which was similar to the Korean (56: 44, p = 0.887) and Western controls (65: 35). In addition, no differences were found between the ESRD and the non-ESRD groups (p = 0.888) or the early hypertension and the normotension groups (p = 0.249). The distribution of alleles for the TGF beta1 Arg25Pro polymorphism showed only the GG type which was different from the Western population controls (G:C = 90:10, p = 0.000). CONCLUSIONS: Our results suggest that the polymorphism at Arg25Pro of TGF-beta1 in the Korean population has an allele distribution different from that ofthe Western population and that the polymorphism at Leu10Pro of TGF-beta1 has no association with the renal progression in Korean ADPKD patients.

Adult↗

PubMed2002

Three novel mutations of the PKD1 gene in Korean patients with autosomal dominant polycystic kidney disease.

Mutations at the PKD1 locus account for 85% of cases of the common genetic disorder called autosomal dominant polycystic kidney disease (ADPKD). Screening for mutations of the PKD1 gene is complicated by the genomic structure of the 5'-duplicated region encoding 75% of the gene. To date, more than 90 mutations of the PKD1 gene have been reported in the European and American populations, and relatively little information is available concerning the pattern of mutations present in the Asian populations. We looked for mutations of the PKD1 gene in 51 unrelated Korean ADPKD patients, using polymerase chain reaction (PCR) with primer pairs located in the 3' single-copy region of the PKD1 gene and by single-strand conformation polymorphism (SSCP) analysis. We found three novel mutations, a G to A substitution at nucleotide 11012 (G3601S), a C to A substitution at nucleotide 11312 (Q3701X), and a C to T substitution at nucleotide 12971 (P4254S), and a single polymorphism involving a G to C substitution at nucleotide 11470 (L3753L). These mutations were not found in control individuals, and no other mutations in the 3' single-copy region of the PKD1 gene of patients with these mutations were observed. In particular, P4254S segregated with the disease phenotype. The clinical data of affected individuals from this study, and of previously reported Korean PKD1 mutations, showed that patients with frameshift or nonsense mutations were more prone to develop end-stage renal failure than those with missense mutations. Our findings indicate that many different PKD1 mutations are likely to be responsible for ADPKD in the Korean population, as in the Western population.

Female↗

PubMed2001

Reproducibility of colonic transit study in patients with chronic constipation.

PURPOSE: Major therapeutic decisions are rendered based on a single colonic transit study. Therefore, the aim of this study was to assess the reproducibility of colonic transit time in patients with chronic constipation. MATERIALS AND METHODS: Fifty-one patients with chronic idiopathic constipation were randomly selected to undergo two separate colonic transit tests. All clinical conditions, methodology, and patients' instructions were identical on both occasions. The gamma rate (linear correlation analysis) was undertaken between the first and second colonic transit times. Groups were divided according to the diagnoses of colonic inertia (slow-transit constipation), paradoxical puborectalis contraction, and chronic idiopathic constipation (normal-transit constipation). RESULTS: In 35 of 51 patients (69 percent), the results were identical between the two studies; however, in 16 patients (31 percent), the results were disparate (gamma correlation coefficient = 0.53; P < 0.01). The specific correlation coefficients for patients with colonic inertia, paradoxical puborectalis contraction, and chronic idiopathic constipation were 0.12, 0.21, and 0.60 (P < 0.01), respectively. Moreover, the success rate of colectomy for colonic inertia was significantly higher in patients who underwent a repeat transit study confirming inertia than in patients who underwent colectomy based on a single study. CONCLUSIONS: Overall, colonic transit time is reproducible in patients with chronic constipation. The correlation coefficient is best for patients with idiopathic constipation and worst for patients with colonic inertia. This new finding suggests that suboptimal surgical outcome may be attributable to inaccurate diagnosis. Because of this poor correlation coefficient, in patients with colonic inertia, consideration should be given to repeating the colonic transit study before colectomy to help secure the diagnosis and improve outcome.

Adult↗

PubMed2001

Genetic heterogeneity in Korean families with autosomal-dominant polycystic kidney disease (ADPKD): the first Asian report.

BACKGROUND: Autosomal dominant polycystic kidney disease (ADPKD) is the most common hereditary renal disease in adults, and the prevalence of this disease within the chronic haemodialysis patient population is known to be approximately 2% in Korea. So far, three genetic locus have been identified as being responsible for ADPKD, and approximately 85% of the cases in Western countries are related to the PKD1 gene. However, little information is available concerning the pattern of linkage analysis in Asian populations. METHODS: 48 families with hereditary renal cysts were recruited by consent and their molecular genetic characteristics were studied. Linkage analysis was done with microsatellite markers (PKD1: SM7, UT581, AC2.5, KG8, D16S418; PKD2: D4S423, D4S1534, D4S1542, D4S1544, D4S2460). Genomic DNA polymerase chain reaction (PCR) and polyacrylamide gel electrophoresis (PAGE) gel run were performed, and the resultant allele patterns were compared with sonographic findings. RESULTS: The results of this study showed that the ratio PKD1:PKD2 was 31:8, and that the PKD2 families exhibited a tendency toward a milder renal prognosis than the PKD1 families. CONCLUSION: We confirmed the applicability of linkage analysis for ADPKD in the Korean population, and our data confirmed a similar incidence of PKD1 (79%) and PKD2 (21%) in Korean patients as in the Western population.

Adolescent↗

PubMed2001

Outcome and management of patients with large rectoanal intussusception.

OBJECTIVES: Rectoanal intussusception is the funnel-shaped infolding of the rectum, which occurs during evacuation. The aims of this study were to evaluate the risk of full thickness rectal prolapse during follow-up of patients with large rectoanal intussusception, and whether therapy improved functional outcome. METHODS: Between September 1988 and July 1997, patients diagnosed with a large rectoanal intussusception by cinedefecography (intussusception > or = 10 mm, extending into the anal canal) were retrospectively evaluated. Patients with full thickness rectal prolapse on physical examination or cinedefecography were excluded, as were patients with colonic inertia or a history of surgery for rectal prolapse. The patients were divided into three groups according to the treatment received: group I, conservative dietary therapy; group II, biofeedback; and group III, surgery. Outcomes were obtained by postal questionnaires or telephone interviews. Parameters included age, gender, past medical and surgical history, change of bowel habits, fecal incontinence score, and development of full thickness rectal prolapse. RESULTS: Of the 63 patients, 18 were excluded (seven patients had confirmed full thickness rectal prolapse, four had previous surgery for rectal prolapse, three had colonic inertia, and four died). Follow-up data were obtained in 36 (80%) of the remaining 45 patients. The mean follow-up of this group was 45 months (range, 12-118 months). There were 34 women and two men, with a mean age of 72.4 yr (range, 37-91 yr). The mean size of the intussusception was 2.2 cm (range, 1.0-5.0 cm). The patients were classified as follows: group I, 13 patients (36.1%); group II, 13 patients (36.1%); and group III, 10 patients (27.8%). Subjectively, symptoms improved in five (38.5%), four (30.8%), and six (60.0%) patients in the three groups (p > 0.05). Among the patients with constipation, the decrease in numbers of assisted bowel movements per week (time of diagnosis to present) was significantly greater in group II compared to group 1 (8.1+/-2.8 vs 0.8+/-0.5, respectively, p = 0.004). Among the patients with incontinence, incontinence scores improved more in group II as compared to either group I or group III (time of diagnosis to present, 3.7+/-4.2 to 1.1+/-5.4 vs 1.4+/-2.2, respectively, p > 0.05). Six patients (two in group I, three in group II, and one in group III) had the sensation of rectal prolapse on evacuation; however, only one patient in group I developed full thickness rectal prolapse. CONCLUSIONS: This study demonstrated that the risk of full thickness rectal prolapse developing in patients medically treated for large intussusception is very small (1/26, 3.8%). Moreover, biofeedback is beneficial to improve the symptoms of both constipation and incontinence in these patients. Therefore, biofeedback should be considered as the initial therapy of choice for large rectoanal intussusception.

Adult↗

PubMed2001

An Epstein-Barr virus isolated from a lymphoblastoid cell line has a 16-kilobase-pair deletion which includes gp350 and the Epstein-Barr virus nuclear antigen 3A.

Epstein-Barr virus (EBV) is associated with human cancers, including nasopharyngeal carcinoma, Burkitt's lymphoma, gastric carcinoma and, somewhat controversially, breast carcinoma. EBV infects and efficiently transforms human primary B lymphocytes in vitro. A number of EBV-encoded genes are critical for EBV-mediated transformation of human B lymphocytes. In this study we show that an EBV-infected lymphoblastoid cell line obtained from the spontaneous outgrowth of B cells from a leukemia patient contains a deletion, which involves a region of approximately 16 kbp. This deletion encodes major EBV genes involved in both infection and transformation of human primary B lymphocytes and includes the glycoprotein gp350, the entire open reading frame of EBNA3A, and the amino-terminal region of EBNA3B. A fusion protein created by this deletion, which lies between the BMRF1 early antigen and the EBNA3B latent antigen, is truncated immediately downstream of the junction 21 amino acids into the region of the EBNA3B sequence, which is out of frame with respect to the EBNA3B protein sequence, and indicates that EBNA3B is not expressed. The fusion is from EBV coordinate 80299 within the BMRF1 sequence to coordinate 90998 in the EBNA3B sequence. Additionally, we have shown that there is no detectable induction in viral replication observed when SNU-265 is treated with phorbol esters, and no transformants were detected when supernatant is used to infect primary B lymphocytes after 8 weeks in culture. Therefore, we have identified an EBV genome with a major deletion in critical genes involved in mediating EBV infection and the transformation of human primary B lymphocytes that is incompetent for replication of this naturally occurring EBV isolate.

Animals↗

PubMed2000

Functional outcomes in patients with mucosal ulcerative colitis after ileal pouch-anal anastomosis by the double stapling technique: is there a relation to tissue type?

PURPOSE: The aim of this study was to evaluate any differences in functional outcome in patients with mucosal ulcerative colitis after restorative proctocolectomy and ileal pouch-anal anastomosis with use of the double stapling technique relative to the type of tissue in the stapled doughnut. METHODS: Between September 1988 and June 1997, the pathology of all patients with mucosal ulcerative colitis who underwent ileal pouch-anal anastomosis with use of the double stapling technique were reviewed. Information was obtained regarding the tissue types in the distal tissue rings (doughnuts) obtained from the stapled ileal pouchanal anastomosis. The level of anastomosis was classified according to the type of tissue in the distal doughnut: Group I- patients in whom the anal transitional zone was removed and the distal doughnut included squamous epithelium or transitional epithelium and Group II- patients in whom the anal transitional zone was preserved because the distal doughnut revealed only columnar epithelium. Functional outcomes were assessed and compared by detailed questionnaires mailed to all patients at least one year after ileal pouch-anal anastomosis surgery. RESULTS: Distal doughnuts were obtained from the stapled ileal pouch-anal anastomosis in 222 patients with mucosal ulcerative colitis. Follow-up data at a mean of 38 (range, 12-132) months were obtained in 138 (62.2 percent) patients, including 72 males, with a mean age of 46.9 (range, 13-79) years. Group I consisted of 40 patients (29 percent; 35 (25.4 percent) who had squamous epithelium and 5 (3.6 percent) who had transitional epithelium in the distal tissue rings). Group II consisted of 98 patients (71 percent) with columnar epithelium in the distal tissue rings. Age at diagnosis and operation, duration of disease, length of follow-up, and stage of pouch surgery were similar in the two groups. Incontinence scores, frequency of bowel movement, use of a protective pad, discrimination between gas and stool, use of antidiarrheals, life-style alteration, and patient satisfaction showed similar functional results between the two groups. CONCLUSIONS: The tissue type in the stapler distal doughnut did not greatly influence functional outcome. Failure to identify a relationship may attest to the variable height and composition of the anal transitional zone.

Adolescent↗

PubMed2000

Desorption behavior of sorbed flavor compounds from packaging films with ethanol solution.

Desorption behavior of sorbed flavor compounds such as ethyl esters, n-aldehydes, and n-alcohols from LDPE and PET films was investigated in 0 to 100% (v/v) ethanol solutions at 20 degrees C, 50 degrees C, and 60 degrees C. In both films, the desorption apparently increased with increasing ethanol concentration and treatment temperature, depending on the compatibility of the flavor compound with the solvent. Namely, the partition coefficient of ethyl esters, n-aldehydes, and n-alcohols in the LDPE film turned out to be approximately zero at >/=60%, >/=80%, and >/=40% (v/v) ethanol, respectively (for PET film, >/=80%, >/=80%, and >/=40% (v/v) ethanol concentrations were required for complete desorption, respectively). As for physical properties (heat of fusion, melting point, and tensile strength and elongation at break) of LDPE and PET films, there were no significant differences between intact film and the treated film with 60% (v/v) ethanol for 30 min at 60 degrees C. These results suggest that it is possible to apply a desorption solvent such as ethanol solution for desorption of sorbed flavor compounds from packaging films with no physical change in the film properties by this desorption treatment.

Ethanol↗

PubMed2000

Clinical status of laparoscopic bowel surgery for GI malignancy.

Laparoscopic colorectal surgery is being utilized increasingly for benign diseases. Recent published series have proven that morbidity and mortality from laparoscopic procedures are superior to those seen after traditional open procedures. However, although the technical feasibility of laparoscopic bowel resections has been confirmed, the oncologic advisability has not. The procedures are not yet standards of care, due to port site recurrences, inadequate lymph node harvest, inadequate resection margins, and level of ligation. At present, laparoscopic bowel resection for cure of malignancy does not confer significant benefits when compared to laparotomy and, indeed, has been associated with some serious problems. Long-term critical evaluation of large numbers of patients in prospective, randomized trials is needed to define any merits of laparoscopy. Until such data become available, laparoscopy for attempted cure of colorectal malignancy should be performed only within the context of peer-reviewed, externally monitored, prospective, randomized trials. However, these techniques are perfectly appropriate for palliation of metastatic disease.

Clinical Trials as Topic↗

PubMed1998

Chinese herbal medicine, sibship, and blood lead in children.

OBJECTIVES: Risk factors for increased blood lead concentration (BPb) has been investigated. However, the effect of sibship and Chinese herbal medicine on BPb has not been systematically studied. In this study BPb data from voluntary testing was used to determine if Chinese herbal medicine and sibship were associated with BPb. METHODS: 319 children aged 1-7 were tested for BPb. Meanwhile, parents were interviewed to obtain information including consumption of Chinese herbal medicine, living environment, lifestyle, and sibship of the children tested. RESULTS: The mean (SD) BPb of 319 preschool children was 4.4 (2.4) micrograms/dl. The consumption of Ba-baw-san (a Chinese herbal medicine) was significantly associated with increased BPb in children (p = 0.038). Further multivariate regression analysis of BPb in 50 pairs of siblings showed the factors of being brothers explained 75% of variation for BPb, and being sisters and brother-sister explained 51% and 41% of variation respectively. CONCLUSION: Chinese herbal medicine and children's play patterns within the family expressed in different types of sibship are the main determinants of low concentrations of BPb in preschool children of Taiwan.

Age Factors↗

PubMed1998

Occupational and environmental lead poisoning: case study of a battery recycling smelter in Taiwan.

The rapid industrialization in Taiwan has caused both prosperity and environmental pollution. The purpose of this study is to demonstrate a case of both occupational and environmental lead poisoning. A patient of lead poisoning initiated a survey of the battery recycling factory, which revealed that 31 of 64 workers suffered from lead poisoning. Children who attended a nearby kindergarten showed a significant increase of blood lead up to 15-25 micrograms/dl and a mild but significant decrease of IQ (intelligent quotient, by Binet-Simon scale) if compared with children of a nonexposed but socioeconomically comparable kindergarten. Outdoor workers of the nearby forging factory also showed a significant increase of blood lead if compared with indoor workers or workers of another nonexposed forging factory 20 Km away. Air sampling showed an average of more than 10 micrograms/m3 in the kindergarten. Soil sampling and analysis also revealed 400 folds increase of lead content, which decreased if the sample was taken deep down to 15-30 cm or 350 meters away from the battery recycling smelter. Moreover, after children were moved away from the pollution source, follow-up examination performed 2.5 years later showed a significant decrease of blood lead and partial recovery of IQ among them.

Adolescent↗

PubMed1997

Environmental arsenic exposure of children around a former copper smelter site.

Arsenic residues in the communities surrounding former smelters remain a public health concern, especially for infants and children. To evaluate environmental exposure among these children, a population-based cross-sectional study was conducted in the vicinity of a former copper smelter in Anaconda, Montana. A total of 414 children less than 72 months old were recruited. First morning voided urine samples and environmental samples were collected for arsenic measurements. The geometric mean of speciated urinary arsenic was 8.6 microg/liter (GSD = 1.7, N = 289). Average arsenic levels of different types of soil ranged from 121 to 236 microg/g and were significantly related to proximity and wind direction to the smelter site. The same significant relationship was observed for interior dust arsenic. Speciated urinary arsenic was found to be significantly related to soil arsenic in bare areas in residential yards (P < 0.0005). In general, elevated excretion of arsenic was demonstrable and warranted parents' attention to reduce exposure of their children to environmental arsenic.

Air Pollution, Indoor↗

PubMed1996

Pollen of a male-sterile mutant of Arabidopsis thaliana isolated from a T-DNA insertion pool is not effectively released from the anther locule.

We have isolated a male-sterile mutant from a pool of T-DNA insertional lines of Arabidopsis thaliana generated by an in planta transformation procedure [Chang et al. (1994) Plant J. 5: 551]. Pollen in this mutant is not effectively released from anther locules after cleavage of the stomium. Most mutant pollen grains are round, in contrast to the tricolpate wild-type pollen, and some pollen grains show an abnormal surface structure. Manually released mutant pollen grains are not fertile and show defects in pollen tube germination in vitro. Genetic analysis disclosed that this lesion is due to a single recessive nuclear mutation located on chromosome 3 closely linked to the gll locus. The mutation locus is tightly linked to the inserted T-DNA.

Arabidopsis↗

PubMed1994

Effect of extracellular calcium depletion on the two-step ANP secretion in perfused rabbit atria.

Employing isolated perfused rabbit atrial model we have found that stretch-activated atrial natriuretic peptide (ANP) secretion takes place in two steps: release of ANP from myocytes into surrounding intercellular space, and then translocation of the released ANP into atrial lumen along with the extracellular fluid (ECF) translocated upon releasing the stretch. Ca2+, one of the most important factors regulating secretory processes, has been reported by many workers to have influence on the ANP secretion, but at large variance. In the present study, therefore, we undertook to clarify the influence of Ca2+ depletion on ANP secretion and further to define which of the two steps is affected by Ca2+ removal. Extracellular Ca2+ depletion resulted in increased basal secretion and in accentuated secretion of immunoreactive (ir) ANP in response to mechanical stimuli. The translocation of ECF increased in response to atrial stretch-and-release, but it was not affected by Ca2+ depletion. The irANP concentration in the extracellular space calculated as the amount of irANP secreted in relation to the ECF translocated significantly increased when extracellular Ca2+ was depleted. These results indicate that extracellular Ca2+ depletion accentuates the stretch-induced ANP secretion through the augmentation of ANP release into the interstitium without changes in the ECF translocation.

Animals↗