Histologic studies of islets of Langerhans in transplanted pancreata from marginal donors in Japan.

The serious shortage of brain-dead donors leads to the use of pancreata from marginal donors, including cardiac death in Japan. We studied the islet histology of pancreas graft biopsies to investigate the adequacy of using pancreata from marginal donors. Pancreas allograft biopsy was performed originally to diagnose acute rejection (Drachenberg grade I-III) at a mean of 6 months after transplantation. The percentage of beta cells showing oxidative DNA changes, replication, and apoptosis was investigated in 7 recipients of simultaneous pancreas-kidney transplantations with good graft function from marginal donors. Their causes of death were cerebrovascular with donor ages >44 years (n = 3), cardiac (n = 2), and cerebrovascular (n = 2). The percentage of beta cells per islet in the transplanted pancreas (71.9 +/- 3.3%) did not correlate with glycemic control or insulin secretion, but did correlated inversely with donor age (r = -0.81; P < .05). Oxidative DNA changes as revealed by 8-hydroxy-2'-deoxyguanosine (8-OHdG) staining were diffusely present in islet cells as well as in the exocrine cells of the transplanted pancreas. The percentage of 8-OHdG-positive cells per pancreas (71.8 +/- 4.5%) did not correlate with glycemic levels, insulin secretion, donor age, or ischemic time. There were no Ki67-positive replicating cells or terminal deoxynucleotide transferase-mediated dUTP nick-end labeling-positive apoptotic islet cells. Transplanted pancreata from marginal donors showed preserved beta cells and function despite diffuse oxidative changes.

A case of recurrent type 1 diabetes mellitus with insulitis of transplanted pancreas in simultaneous pancreas-kidney transplantation from cardiac death donor.

AIMS/HYPOTHESIS: A 41-year-old woman undergoing simultaneous pancreas-kidney transplantation from an HLA-mismatched cardiac death donor abruptly developed overt hyperglycaemia under standard immunosuppressive therapy at 48 months after transplantation. Unexpectedly, we found insulitis in the transplanted pancreas and characterised the insulitis. METHODS: Pancreas graft biopsies were performed 3 years before and after the development of hyperglycaemia and the specimens were examined histologically. RESULTS: Insulitis was absent in the first biopsy, although oxidative DNA changes revealed by 8-hydroxy-2'-deoxyguanosine (8-OHdG) staining were diffusely present both in islet cells and exocrine cells. No Ki67-positive proliferating cells were seen in the islets. Anti-glutamic acid decarboxylase antibody was undetectable 6 months earlier but increased to 6.3 U/l at the development of hyperglycaemia. The level of anti-insulinoma-associated protein 2 antibody was 18.5 U/l. Insulin secretion was severely suppressed and insulin therapy was resumed. In the second biopsy, although acute allograft rejection was minimal, insulin-positive beta cells were markedly reduced, and glucagon-positive alpha cells predominated. CD3-positive T lymphocytes, CD8-positive cytotoxic T lymphocytes and CD68-positive macrophages infiltrated around and into islets. The infiltrating cells expressed Fas ligand as well as granzyme B. More than 80% of islets were affected by insulitis. 8-OHdG-positive cells were also present in islets and exocrine tissue. The percentage of Ki67-positive cells in total islet cells was 1.5%. There were no TUNEL-positive apoptotic cells in the islet cells. CONCLUSIONS/INTERPRETATION: The histological features of insulitis in transplanted pancreas were consistent with common type 1 diabetes mellitus, but the clinical course of the recurrence appeared to be more rapid.

Spontaneous acute subdural haematoma and intracerebral haemorrhage in patient with HELLP syndrome: case report.

HELLP (haemolysis, elevated liver enzymes, and low platelet count) syndrome can result in a fatal intracranial haemorrhage during the perinatal period. We report treatment of a 32-year-old primigravida who fell into a deep coma during labour with fetal distress, complicated by a spontaneous acute subdural haematoma and intracerebral haemorrhage. Simultaneous emergency operations, evacuation of the acute subdural haematoma and a caesarean section, were performed, during which a diagnosis of HELLP syndrome with disseminated intravascular coagulation was made. Both mother and infant recovered, though hemiparesis persisted in the mother. Patients with HELLP syndrome should be managed as high-risk, which requires an excellent working relationship of the physicians involved. Prompt recognition of intracranial haemorrhagic complications and neurosurgical intervention are particularly important.

Serum high-molecular weight adiponectin is related to early postprandial glycemic increases and gastric emptying in patients with type 2 diabetes mellitus.

BACKGROUND: Postprandial hyperglycemia and hyperlipidemia are frequently associated with type 2 diabetes mellitus. The aim of the present study is to investigate the clinical determinants of postprandial glycemia and lipemia, especially serum high-molecular weight adiponectin. METHODS: Twenty-seven diabetic patients treated with diet alone and 13 healthy volunteers took liquid test meal containing 53 g carbohydrate and 47 g lipid, dosed with nonradioactive isotope (13)C-acetate. Venous blood and breath samples were obtained for 180 min after the meal. Gastric emptying was evaluated by peak excretion time of (13)CO(2) in the breath samples. Delayed gastric emptying was defined as peak excretion time > 2.5 h (mean + 2 SD in the healthy volunteers). RESULTS: Diabetic patients showed delayed insulin secretion, postprandial hyperglycemia and hyperlipidemia compared with control. Postprandial glycemic increases significantly correlated with enhanced gastric emptying. Serum high-molecular weight adiponectin correlated with postprandial glycemic increases at 30 and 60 min after meal (r = 0.42, p < 0.05; r = 0.37, p < 0.05, respectively). Serum high-molecular weight adiponectin also correlated with gastric emptying (versus peak excretion time r = - 0.58, p < 0.05). In addition, diabetic patients with delayed gastric emptying showed the suppressed postprandial glycemia with lower serum high-molecular weight adiponectin than those with normal gastric emptying. On the other hand, postprandial increases in serum triglyceride were not related to serum high-molecular weight adiponectin or gastric emptying, but significantly related to liver function test (serum transaminases) and body mass index. CONCLUSIONS: Early postprandial glycemic increases were related to elevated serum high-molecular weight adiponectin, which might be associated with enhanced gastric emptying.

Detection of mitochondrial DNA nucleotide 11778 point mutation of Leber hereditary optic neuropathy from archival stained histopathological preparations.

PURPOSE: We evaluated the availability of archival histopathological preparations for genetic diagnosis of Leber hereditary optic neuropathy (LHON). METHODS: Preparations of various tissues of an autopsied case of LHON, and of the optochiasmal arachnoidea of nine cases of bilateral optic neuropathy (BON) were studied to determine the presence of a point mutation of the mitochondrial DNA nucleotide (nt) 11778 using PCR method. RESULTS: An nt11778 point mutation was detected in all preparations of the autopsied case. Five preparations out of six BON cases who were diagnosed as LHON based on positive family history, revealed this point mutation. This mutation was also detected in two of three BON patients with no family history of the disease. CONCLUSION: The archival preparations were found to be available as materials of genetic diagnosis for LHON, which indicated that it would be capable to reevaluate retrospectively the pedigree of LHON and BON cases.

Poly(ethylene glycol) derivative of cholesterol reduces binding step of liposome uptake by murine macrophage-like cell line J774 and human hepatoma cell line HepG2.

Liposome uptake by HepG2 human hepatoma cells was investigated in comparison with the uptake by J774 murine macrophage-like cells. HepG2 cells accumulated liposomes (egg yolk phosphatidylcholine (EPC)/Chol; 75/25, diameter 0.2 micron) at 37 degrees C comparably to J774 macrophage-like cells. Confocal microscopic observations revealed that J774 cells internalized EPC/Chol liposomes efficiently but HepG2 cells kept most of the liposomes bound on their plasma membrane surfaces. Poly(ethylene glycol) (PEG)-coated liposomes (0.2 micron) containing poly(ethylene glycol) cholesteryl ether (PEG-Chol) avoided cellular uptake at 37 degrees C by either cell line. In both cell lines, binding of PEG-coated liposomes was lower than that of EPC/Chol liposomes when incubation was carried out at 4 degrees C. To analyze the binding process at 37 degrees C, surface-bound liposomes were removed from the cells by pronase treatment. A reduction of the amount of bound-liposomes on cell surfaces was observed in the case of PEG-coated liposomes. Therefore, PEG-coating reduces direct binding of liposomes to the cell surfaces. The presence of apolipoprotein E (apoE) increased the uptake to EPC/Chol liposomes via its receptor in both cell lines. In contrast, cellular uptake of PEG-coated liposomes was not enhanced by treatment with apoE. Therefore, while apoE-mediated liposome uptake occurs in the case of EPC/Chol liposomes, it does not occur for PEG-coated liposomes; PEG-coating also inhibits protein-mediated binding to the cells. These results further imply that elusion from liver clearance of PEG-coated liposomes is not only due to the reduction of uptake by Kupffer cells but also by hepatocytes when liposomes are small enough to go through the fenestrates of the endothelial lining.

[A study on the maternal plasma C21 steroids concentration during pregnancy].

During pregnancy, C21 steroids such as progesterone (P4), and cortisol (F), have been reported to be closely involved in uterine contraction. To clarify the association between changes in steroid hormones and the onset of delivery, we measured the concentrations of six C21 steroids in maternal blood by high performance liquid chromatography. Changes in each steroid hormone were evaluated by analysis of variance during pregnancy. Pregnenolone, a source of C21 steroids, gradually increased during pregnancy. P4 and 17P4, its metabolite, reached a peak 3 weeks before delivery and noticeably decreased thereafter. Accompanying a decrease in P4 and 17P4, 20P4 and F, its metabolite, were noticeably increased. The association among these steroid hormones was also evaluated. The correlation between P4 and F was reversed after 3 weeks before delivery. These results suggest that steroid hormones in the maternal blood begin to change dynamically about 3 weeks before delivery. In particular, a decrease in P4 and an increase in F seem to be closely related to the onset of delivery.

Vasomotor nerves of vessels in the human optic nerve.

Aminergic and cholinergic vasomotor nerves in vessels of the human optic nerve were studied morphologically. Aminergic nerve fibers were observed by the glyoxylic acid method. Cholinergic nerve fibers were observed by light microscopy after acetylcholinesterase staining by the Karnovsky-Roots method and Tago's modified method. In the retrobulbar optic nerve behind the bulbus, aminergic and cholinergic vasomotor nerves were observed to be dense in the central retinal artery and vein and posterior ciliary arteries. A large number of vasomotor nerves were also demonstrated in vessels in the septum of the optic nerve, but they were sparse in pial vessels. Further centrally, a few vasomotor nerves were found in pial vessels of the intracanalicular and intracranial optic nerve, but few were observed in the septum of the optic nerve. At the optic chiasm they were densely distributed in pial vessels.

The regulation of oxytocin receptor expression in human myometrial monolayer culture.

Clarification of the mechanism of oxytocin (OT)-induced contraction of the uterus seems to be essential for the elucidation of the mechanism of the initiation of labor. Although it has been suggested that estradiol (E) and progesterone (P) are involved in the expression of oxytocin receptors (OTRs), no consensus opinion has been formed on this topic. Thus we recently assessed the effects of E and P on OTR expression using cultures of human uterine cells and we examined the changes in the expressed OTRs following treatment of the cell with exogenous OT. The following results were obtained: 1. The total cellular concentration of OTRs as measured in the myometrial crude membrane fraction (total OTR concentration) showed an increase dependent on the E concentration and on the length of the incubation period in the presence of E. This increase following treatment with E (10(-7) M) was suppressed by simultaneous treatment with P in a concentration-dependent manner; being suppressed by 50% when the concentration of P was 2.7 x 10(-6) M (E/P ratio = 0.037). When 1 nM OT was added to the culture, the total OTR concentration did not change within the first 30 minutes of incubation, but decreased by about 70% twenty-four hours after addition of OT. 2. The concentration of OTRs at the cell surface (surface OTR concentration), as measured in myometrial cells that adhered to the culture plate, did not change with time when the cells were cultured at 4 degrees C in the presence of 1 nM OT. However, when cultured at 37 degrees C, the surface OTR concentration showed decreases dependent on the concentration of OT added and the time after the addition of OT. This change was observed within 60 minutes after the addition of OT to the culture. This decrease in surface OTR concentration was suppressed by concanavalin A (ConA), an inhibition of the internalization of cell surface receptors. These results indicate that in humans also, the expression of myometrial OTRs is regulated by change in the E/P ratio. The present study also revealed that OTRs, once expressed, soon disappear from the cell surface in the presence of exogenous OT (due to internalization of OTRs, i.e., dislocation of OTRs from the cell surface to the inside of the cells), and that prolonged exposure to OT even leads to the disappearance of intracellular OTRs. The present study thus suggests that the expression of human myometrial OTRs is regulated by E and P, and that an agonist-induced desensitization mechanism at the receptor level, similar to that reported for beta-adrenergic receptors, is also operating in this receptor.

[A study on the effect of cortisol and progesterone on cytosolic arachidonic and palmitic acid concentrations in cultured human myometrial cells].

Glucocorticoids inhibit prostaglandin synthesis in several cell types, presumably by inhibiting arachidonic acid deacylation from phospholipids. We studied the effects of cortisol (F) and progesterone (P) on fatty acid release from cultured human myometrial cells. Confluent monolayer cultures of myometrial cells were adapted to steroids containing medium for 24 hours and the intracellular arachidonic acid and palmitic acid concentrations were determined. In the presence of fetal calf serum (FCS), the palmitic acid concentrations significantly decreased after the addition of 10(-7)M F. In the absence of FCS, the concentrations of both fatty acids were markedly increased after the addition of F. During oxytocin stimulation, the arachidonic acid concentration did not change but the palmitic acid concentration decreased slightly after the addition of F. A similar evaluation was done with P. The palmitic acid concentration decreased slightly after the addition of 10(-5)M P in the presence of FCS but increased markedly in the absence of FCS. During stimulation with oxytocin, the fatty concentrations of fatty acids decreased significantly in a dose-dependent manner. These results suggest that both F and P are implicated as regulatory factors in the activation of arachidonic acid cascade.

[Effect of progesterone, cortisol and dehydroepiandrosterone-sulfate on prostaglandin production by cultured human myometrial cells].

Prostaglandins (PGs) are considered to play important roles as contraction regulating factors in the mechanism of human uterine contraction. On the other hand, steroid hormones released in large amounts in late pregnancy appear to be closely related to the maintenance of pregnancy, fetal growth, and onset of delivery. To clarify the interactions between PGs and steroid hormones, we studied PGE2 and 6-keto-PGF1 alpha production on human myometrial cell culture. Cultures of myometrial cells from premenopausal patients with benign uterine diseases were established, and PG production in serum-free media and in the presence of various concentrations of progesterone (P), cortisol (F) and dehydroepiandrosterone-sulfate (DHAS) was studied. The following results were obtained: 1) The PGE2 and 6-keto-PGF1 alpha concentrations were 1,410.4pg/ml and 600pg/ml at 10 minutes after changing the medium, decreased transiently at 30-60 minutes, and increased thereafter. 2) When the cells were cultured with various concentration of P for 24 hours, PGE2 production was suppressed in the presence of P at 10(-7)M or above, but 6-keto-PGF1 alpha production showed a significant dose-dependent increase. 3) In the presence of F, PGF2 production shows a dose-dependent increase at high doses, but 6-keto-PGF1 alpha production markedly decreases at 10(-6)M or above. 4) In the presence of DHAS, PGE2 production increased markedly at 10(-6)M or above. These findings indicate that steroid hormones are regulatory factors in the production of PG by the myometrium.

[The regulation of human myometrial oxytocin receptor expression by oxytocin].

Myometrial contraction induced by oxytocin (OT) is dependent on the OT concentration and the number of OT receptors (OTR) expressed. We previously reported that the number of myometrial OTR expressed is regulated by estradiol and progesterone in myometrial cell culture. In the present study, we evaluate the change in the number of OTR expressed on the cell surface after the addition of OT. After OT was added under various conditions to myometrial cells, we measured the number of OTR expressed on the cell surface (surface-OTR) and those in the plasma membrane (PM) (total-OTR). 1. After the addition of 1 nM OT, total-OTR was 25.78 fmol/mg protein in the OT-negative control and was 23.66 and 7.88 at 30 minutes and 24 hours. 2. Surface-OTR showed no changes after the addition of 1 nM OT at 4 degrees C, and the value after 60 minutes was 8.90 fmol/mg protein. At 37 degrees C, however, it become 5.53 and 1.72 fmol/mg protein 60 minutes after the addition of OT at 10pM and 10nM. This decrease in surface-OTR was suppressed by concanavalin A (ConA), which inhibits the internalization of receptors. Our study demonstrated that OTR expressed on the surface of myometrial cells decreased rapidly in the presence of OT due to internalization.

[Effects of steroid hormones on change in [Ca2+]i and on PI response following oxytocin stimulation in cultured human myometrial cells].

In oxytocin (OT)-induced myometrial contraction, it is considered that Ca2+ release associated with activation of PI response is the main cascade. Steroid hormones such as dehydroepiandrosterone-sulfate (DHAS), progesterone (P), and cortisol (F), which show diverse changes during pregnancy, are considered to be involved in myometrial contraction at the onset of delivery. In this study, we examined changes in the intracellular Ca2+ concentration ([Ca2+]i) and PI response under OT stimulation. (1) After cultured human myometrial cells were incubated for 48 hours in a medium containing 10(-6) M of DHAS, P, or F, [Ca2+]i was measured with an OLYMPUS OSP3 by using the fluorescent Ca2+ indicator Fura2-AM. When the maximum change in [Ca2+]i under stimulation with 10(-8) M OT was regarded as 100% (control), it was increased significantly to 121.1 +/- 9.8% in the cells treated with F, but was reduced to 89.4 +/- 4% in those treated with P. It was increased to 107.5 +/- 6.9% in the cells treated with DHAS, but the difference was not significant. (2) After loading with 5 microCi 3H myo-inositol and various steroid hormones for 24 hours in the cells, the intracellular IP1-3 production under stimulation with 10(-8) M OT was examined. IP1-3 production and IP total production (IPn) were significantly increased in the cells treated with F as compared with the control, but IPn was reduced by about 40% in the cells treated with 10(-6) M P. And in the cells treated with DHAS, IPn was slightly increased.(ABSTRACT TRUNCATED AT 250 WORDS)

[A case of suprasellar arachnoid cyst followed up for a long time].

We followed a case of suprasellar arachnoid cyst for 12 years. The patient was a sixteen-year-old girl without particular problems in her general condition. She showed optic atrophy in both eyes and optic nerve hypoplasia with an inferotemporal quandranopsia in the left eye. A suprasellar arachnoid cyst communicating with the tubarachnoid space was found to extend into the sella turcica as an empty sella. A cyst wall was resected and a cyst-peritoneal shunt performed. After 12 years from the operation, sensitivity was slightly depressed in the visual field where it had already been disturbed. Although there are few reports in the literature on involvement of the optic nerves and chiasma by suprasellar arachnoid cysts, papilledema and optic atrophy are often found in children, and infero-temporal quandranopsia or homonymous hemianopsia have been reported. Visual field defects were most likely caused by compression of the optic nerve by cyst or prolonged papilledema. We also suspect that some kind of disturbance to the optic nerve occurred during extension of the arachnoid cyst as an empty sella, or during formation of arachnoid cyst in the fetus stage.

[The mechanism of beta-receptor desensitization in human myometrial culture cell].

Beta-adrenoceptor desensitization is considered to be primarily due to phosphorylation of receptors by protein kinase A (PKA) and beta-adrenaline receptor kinase (beta-ARK) and sequestration of receptors themselves. But in the human uterine muscle, the desensitization mechanism has been evaluated only as a phenomenon, and there are few studies on its mechanism. We evaluated cAMP production by beta-agonist and changes in the number of beta-receptors in cultured human myometrial cells. Uterine muscle cell were obtained from patients with benign disease before menopause and cultured. 1) At the confluent stage, dl-Isoproterenol Hydrochloride (ISP) was added under various conditions, and the intracellular cAMP concentration was determined by EIA. 2) After the addition of ISP (10(-6) M), plates were incubated at 37 degrees C, and beta-AR on the cell membrane surface (S beta-AR) and total beta-AR (T beta-AR) was measured in a binding assay with 125I-pindolol. The production of cAMP dose-dependently increased 30 minutes after the addition of ISP at 10(-6) M or higher, but rapidly decreased thereafter. T beta-AR was similar in the cells treated with ISP (10(-6) M) and the untreated cells. On the other hand, S beta-AR decreased by about 50% in the ISP treated cells. These result suggest the desensitization of beta-AR in human uterine muscle, and the involvement of the sequestration mechanism as its cause.

A case-control study on risk factors for leukemia in a district of Japan.

A case control study was performed with 142 leukemia patients and 284 controls matched for age and sex. Occupation, birth order, past medical history, and drinking and smoking habits were compared in these two groups. Persons born first or fourth were found to have a higher incidence of leukemia. History of a fracture was one of the risk factors for acute leukemia, and a history of gastroduodenal ulcer was a risk factor for chronic leukemia. This may suggest that extensive exposure to X-rays in diagnosis and treatment is a risk factor for leukemia. There was a significant dose-response relationship between the amount of smoking and the incidence of acute nonlymphocytic leukemia, but not between the amount of alcohol consumption and the incidence of leukemia. Thus, smoking was one of the risk factors for acute leukemia.

[The effect of oxytocin on production of free fatty acid in primary human uterine myometrial cell culture].

Oxytocin(OT) is considered to have several activities besides strongly inducing myometrial contraction by activating phosphatidilinositol-specific phospholipase C(PI-PLC). These include reconstructing the phospholipid constituents of the cell membrane and activating a variety of fatty acid producing systems. On the other hand, pregnancy-related steroid hormones which are produced by the fetus, placenta and mother are considered to be closely involved in the maintenance of pregnancy and the initiation of labor. In the present study with cultured myometrial cells, we examined what effect these steroid hormones might exert on the intramyometrial production of fatty acid by OT. Our results confirmed bi-phasic production of arachidonic acid(AA), linoleic acid(LA), palmitic acid(PA), and stearic acid(SA) by OT. Phase 1 was an increasing but transient phenomenon having its peak at 30 sec. It is considered to be derived from phosphatidylinositol bis-phosphate. Phase 2 was a persistent and increasing phenomenon which was initiated after 120 sec. It is considered to be mediated by Ca-dependent phospholipase. We also studied the effect of steroid hormones on the production of fatty acid. For AA, LA, and PA, we confirmed that dehydroepiandrosterone sulfate(DHAS) shortened the time taken in reaching the peak of Phase 1 to half of that of the control, and progesterone(P) extended the time 2-3 fold. These findings suggest that DHAS, P and F might modify the human myometrial construction mechanism as a factor which regulates the quantity and velocity of fatty acid production.

[The effect of steroid hormone on oxytocin receptor expression in primary human uterine myometrial cell culture].

In the present study, we have examined the steroid hormone effect on oxytocin receptor (OTR) expression in human myometrial monolayer culture. The myometrial cells were cultured for 24-72 hours in serum-free media with various concentrations of steroid hormones. The plasma membrane of the cultured cells was then collected. The 125I-oxytocin(OT) was employed for a binding assay and the mean binding and dissociation constant were evaluated by Scatchard analysis. 1. The OT binding values in the presence of estradiol free, 10(-8) M, and 10(-7) M at 72 hours were 19.85, 28.12, and 36.20pM/mg protein, respectively. 2. The OT binding values in the presence of estradiol (10(-7) M) at 24, 48, and 72 hours were 17.85, 23.72, and 36.20pM/mg protein, respectively. 3. Dehydroepiandrosterone sulfate (10(-5) M) exerted almost no effect on the OTR expression by estradiol (10(-7) M). Cortisol (10(-5) M) decreased the amount of OTR expressed by estradiol. 4. The changes in OTR expression caused by estradiol (10(-7) M) were inhibited according to the concentration by progesterone. The concentration of progesterone at which OT binding was reduced 50% was 2.7 x 10(-6) M (E/P ratio = 0.037). These results suggested that estradiol increased the amount of OTR discovered in human myometrial cells in a time and concentration dependent manner, while progesterone inhibited the changes in OTR expression by estradiol in a concentration dependent manner. Thus, it was indicated that the changes in the E/P ratio during pregnancy which regulate the OTR expression control the myometrial contraction.

[Effects of steroid hormones on change in [Ca2+]i following oxytocin stimulation in cultured human myometrial cells, and on myometrial oxytocin receptor].

It is considered that steroid hormones, the concentrations of which vary during pregnancy, play an important role in the initiation of delivery. In the present study, we measured intracellular Ca2+ ([Ca2+]i) change following oxytocin stimulation in cultured human myometrial cells with fura-2, a fluorescent Ca2+ indicator. We also studied the effect of the steroid hormones on changes in [Ca2+]i due to oxytocin stimulation. When the [Ca2+]i change due to 10(-6) M oxytocin reached 100%, the addition of 10(-6) M DHAS (dehydroepiandrosterone sulfate) just before the stimulation raised the [Ca2+]i level to 207%, whereas that of 10(-6) M progesterone dropped to 64%. Moreover DHAS accelerated the speed of increase until the maximum response of [Ca2+]i, while progesterone decelerated it. In another study, human myometrial plasma membrane was solubilized in 7.5mM CHAPSO solution and applied to a binding study. Oxytocin receptors of two different molecular weights, namely 350kD(OTR-1) and 39kD(OTR-2), were extracted from solubilized plasma membrane by employing a gel filtration column. Binding assays were performed for OTR-1 and OTR-2 in the presence of DHAS and progesterone (10(-5) M). The results showed that DHAS enhanced the binding affinity of the receptors, whereas progesterone reduced the maximum binding capacity. It is therefore considered that the steroid hormones added just before oxytocin stimulation might act on receptor levels and modify intracellular Ca2+ response over short periods.