Summary of results of serological tests and diagnoses for 4774 cases of various autoimmune bullous diseases consulted to Kurume University.

BACKGROUND: Although many new disease entities of autoimmune bullous disease (AIBD) have recently been recognized, satisfactory immunological diagnostic methods and comprehensive classifications for various AIBDs have not been established. OBJECTIVES: To identify immunological diagnostics and comprehensive classifications for AIBDs. METHODS: We selected and examined 4774 patients with various AIBDs from our cohort of 5063 patients with difficult AIBDs, whose sera and information were sent for our diagnostic method from other institutes in either Japan or other countries over the last 19 years. We examined the sera by our immunological diagnostic methods including various immunofluorescence, immunoblotting and enzyme-linked immunosorbent assay tests to make final diagnoses. RESULTS: By our immunological diagnostic methods, we successfully made final diagnoses for approximately three-quarters of the difficult cases of AIBD, although the remaining cases could not be diagnosed. Using the results, we suggest the most extensive and newest classification of AIBDs, and also propose the most efficient algorithm of immunological tests for the diagnosis of various AIBDs. CONCLUSIONS: The results in this study of 4774 patients with various AIBDs indicate that our immunological diagnostic method is useful for making diagnoses for most patients with AIBD. However, we need further improvements including new immunological techniques to establish more satisfactory methods.

Clinical and immunological profiles in 17 Japanese patients with drug-induced pemphigus studied at Kurume University.

BACKGROUND: Drug-induced pemphigus (DIP) shows clinical, histopathological and immunological features of pemphigus. However, little is known about immunological profiles in DIP. OBJECTIVES: To characterize clinical and immunological profiles in patients with DIP. METHODS: We studied 17 Japanese patients with DIP who were treated at Kurume University Hospital or who consulted from other hospitals between 1997 and 2012. Complicated diseases, clinical and histopathological manifestations, responsible drugs and findings in immunofluorescence, enzyme-linked immunosorbent assays (ELISAs), immunoblotting (IB) and prognosis were analysed. RESULTS: Eight of the 17 patients with DIP showed pemphigus foliaceus-like appearance, three showed pemphigus herpetiformis-like appearance, and six showed atypical bullous lesions. Responsible drugs were thiol-containing drugs in 16 patients (bucillamine in nine cases, d-penicillamine in four cases, and cetapril, thiopronine and captopril in one patient each), and a nonthiol drug, sulfasalazine, in one patient. By ELISAs and/or IB analyses, nine patients reacted only with desmoglein 1 (Dsg1), four reacted with Dsg1 and Dsg3, and four showed no specific reactivity. By IB of normal human epidermal extracts, in addition to positive reactivity with Dsg1, four patients with no detectable malignancy showed paraneoplastic pemphigus-like reactivity with the 210-kDa envoplakin and the 190-kDa periplakin. Four cases showed anti-Dsg3 antibodies without mucosal lesions. While 11 cases recovered after discontinuation of the causative drugs, six patients had a very protracted or intractable disease course, and might develop true pemphigus. CONCLUSIONS: The present study indicated that the majority of the patients with DIP studied showed a pemphigus foliaceus-type phenotype with anti-Dsg1 autoantibodies, caused by thiol-containing drugs.

Five Japanese cases of antidesmoglein 1 antibody-positive and antidesmoglein 3 antibody-negative pemphigus with oral lesions.

BACKGROUND: Oral mucosal lesions develop in pemphigus vulgaris, but not in pemphigus foliaceus. This clinical phenomenon is explained by the 'desmoglein (Dsg) compensation theory'. Dsg3 and Dsg1 are major autoantigens for pemphigus vulgaris and pemphigus foliaceus, respectively. Dsg3 is overexpressed and Dsg1 is weakly expressed on the oral mucosa. Thus, on the oral mucosa, suppression of Dsg3 function by anti-Dsg3 autoantibodies is not compensated by weakly expressed Dsg1 in pemphigus vulgaris, while suppression of Dsg1 function by anti-Dsg1 autoantibodies is perfectly compensated by richly expressed Dsg3 in pemphigus foliaceus. OBJECTIVES: We present five Japanese patients with pemphigus who deviate from this theory, i.e. all patients showed oral lesions (three also had cutaneous lesions) and reacted only with Dsg1, but not with Dsg3, by enzyme-linked immunosorbent assay. METHODS: To confirm whether the unique clinical phenotypes in our patients were due to a different immunological profile from that in classical pemphigus, we examined the reactivity of the patient sera by immunoprecipitation-immunoblotting analysis using five Dsg1/Dsg2 domain-swapped molecules. RESULTS: The sera of two patients who had only oral lesions tended to react with the extracellular (EC) 5 domain of Dsg1, the domain that is considered nonpathogenic in classical pemphigus foliaceus. Sera of three patients with mucocutaneous lesions reacted with EC1 domain or with both EC1 and EC2 domains of Dsg1, like classical pemphigus foliaceus. CONCLUSIONS: These results indicate that antigenic diversity of anti-Dsg1 antibodies in these patients may cause the unique oral mucosal and cutaneous lesions, although further studies are required to elucidate the pathomechanisms.

Subcellular distribution of envoplakin and periplakin: insights into their role as precursors of the epidermal cornified envelope.

Envoplakin and periplakin are two plakins that are precursors of the epidermal cornified envelope. We studied their distribution and interactions by transfection of primary human keratinocytes and other cells. Full-length periplakin localized to desmosomes, the interdesmosomal plasma membrane and intermediate filaments. Full length envoplakin also localized to desmosomes, but mainly accumulated in nuclear and cytoplasmic aggregates with associated intermediate filaments. The envoplakin rod domain was required for aggregation and the periplakin rod domain was necessary and sufficient to redistribute envoplakin to desmosomes and the cytoskeleton, confirming earlier predictions that the proteins can heterodimerize. The linker domain of each protein was required for intermediate filament association. Like the NH(2) terminus of desmoplakin, that of periplakin localized to desmosomes; however, in addition, the periplakin NH(2) terminus accumulated at cell surface microvilli in association with cortical actin. Endogenous periplakin was redistributed from microvilli when keratinocytes were treated with the actin disrupting drug Latrunculin B. We propose that whereas envoplakin and periplakin can localize independently to desmosomes, the distribution of envoplakin at the interdesmosomal plasma membrane depends on heterodimerization with periplakin and that the NH(2) terminus of periplakin therefore plays a key role in forming the scaffold on which the cornified envelope is assembled.

Expression of angiogenesis-related genes regulates different steps in the process of tumor growth and metastasis in human urothelial cell carcinoma of the urinary bladder.

OBJECTIVE: This study was designed to determine the relative activity of angiogenesis-related genes in the regulation of tumorigenicity and subsequent metastases of urothelial cell carcinomas (UC) of the urinary bladder. METHODS: We selected the clones with the highest and lowest expression level of basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF)/vascular permeability factor or interleukin-8 (IL-8) in the highly tumorigenic and metastatic human UC cell line 253J B-V. Tumorigenicity and production of spontaneous lymph node metastases were evaluated 1, 2, 4, 8 and 12 weeks after orthotopic implantation of each specific expression clone into the urinary bladder of athymic nude mice. Moreover, the transitional changes in the expression of angiogenesis-related genes and neovascularization were determined in tumors and metastases. RESULTS: At the early stage of tumor growth following orthotopic implantation, tumorigenicity and metastases were significantly increased in the clones with the highest expression of bFGF and IL-8, while they were significantly inhibited in the clones with the lowest expression of bFGF and IL-8 compared to parental 253J B-V. In the tumors, specific expression of angiogenesis-related genes and intratumor neovascularity of each clone were gradually regulated to the same level as parental 253J B-V. In metastasized tumors of the highest and lowest IL-8-expressing clones, IL-8 expression was consistently high and low, respectively. CONCLUSIONS: These findings indicate that at the early stage of tumor growth, bFGF and IL-8 expression play important roles in the regulation of angiogenesis, tumorigenicity and subsequent metastases of human bladder cancer.

A clinical study of patients with pemphigus vulgaris and pemphigus foliaceous: an 11-year retrospective study (1996-2006).

Only a few reports have been published of detailed clinical studies of pemphigus in Japan. The aim of this study was to determine the clinical characteristics of patients with pemphigus vulgaris (PV) and pemphigus foliaceous (PF), who were newly diagnosed in the dermatology department of Kurume University Hospital, Japan, over the past 11 years. The primary site of involvement was the oral mucosa in 21 patients (75%) with PV. At the initial visit, most of the patients with PV had moderate to severe disease. With regard to management, systemic corticosteroids were the mainstay of treatment for patients with PV, and plasmapheresis was the most frequently used adjuvant therapy. Dapsone was the mainstay of treatment for the patients with PF. The patients were investigated for any association with an underlying malignancy; in patients with PV, lung, stomach and uterine cancers (one patient each) were seen.

The prognostic value of angiogenesis factor expression for predicting recurrence and metastasis of bladder cancer after neoadjuvant chemotherapy and radical cystectomy.

To determine the prognostic value of angiogenesis factor expression for patients with muscle-invasive transitional cell carcinoma (TCC) of the bladder treated with neoadjuvant methotrexate, vinblastine, doxorubicin, and cisplatin (M-VAC) chemotherapy and radical cystectomy, we evaluated the expression of basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF), and interleukin 8 (IL-8) by in situ hybridization, and we determined microvessel density (MVD) by immunohistochemistry. These factors were evaluated in 55 biopsy specimens prior to therapy and in the cystectomy specimens of 51 patients after completion of therapy. By univariate analysis, VEGF expression and MVD in the biopsy specimens were significant predictors of disease recurrence. By multivariate analysis, only VEGF expression was an independent prognostic factor. Pathological stage, bFGF expression, and MVD in the cystectomy specimens after therapy were all independent prognostic factors for disease recurrence. The results of this exploratory study indicate that the expression levels of VEGF and bFGF as indicated by in situ hybridization and MVD as indicated by immunohistochemistry identify patients with muscle-invasive TCC who are at high risk of developing metastasis after aggressive therapy with systemic M-VAC chemotherapy and radical cystectomy.

Treatment of human metastatic transitional cell carcinoma of the bladder in a murine model with the anti-vascular endothelial growth factor receptor monoclonal antibody DC101 and paclitaxel.

Vascular endothelial cell growth factor (VEGF) regulates angiogenesis and metastasis of bladder cancer (transitional cell carcinoma, TCC) through binding to VEGF receptor-2 (VEGFR-2). In this study, we evaluated whether the anti-VEGFR monoclonal antibody (Mab) DC101 in combination with paclitaxel inhibited tumorigenesis, angiogenesis, and metastasis of human TCC growing within the bladder of athymic nude mice. In vivo therapy with Mab DC101 and paclitaxel induced significant regression of bladder tumors compared with either agent alone. Median bladder weights were reduced from 601 mg in untreated controls, 422 mg in mice treated with paclitaxel alone (P < 0.005), 361 mg in mice treated with DC101 alone (P < 0.005), and 113 mg in mice that received combination therapy (P < 0.0005). Only one of nine mice developed spontaneous lymph node metastasis after combined treatment, compared with seven of seven untreated controls (P < 0.0005), six of eight after DC101 (P < 0.01), and five of eight mice after paclitaxel (P < 0.05). Combined treatment with both paclitaxel and DC101 inhibited tumor-induced neovascularity compared with all other groups (P < 0.005), without altering the expression of VEGF or flk1. Mab DC101 and paclitaxel combined enhanced apoptosis in the tumor and endothelial cells compared with other treatment (P < 0.005). These studies indicate that Mab DC101, which blocks VEGFR-2 function, has significant efficacy against human TCC, especially when combined with the chemotherapeutic agent paclitaxel. The antitumor effect was mediated by inhibition of angiogenesis and induction of both tumor cell and endothelial cell apoptosis.

Treatment with low-dose interferon-alpha restores the balance between matrix metalloproteinase-9 and E-cadherin expression in human transitional cell carcinoma of the bladder.

Tumor invasion and metastasis are regulated by the expression of genes such as E-cadherin, which regulates cell adhesion, and matrix metalloproteinase-9 (MMP-9), which alters the integrity of the extracellular matrix. Both up-regulation of MMP-9 and down-regulation of E-cadherin correlate with bladder cancer metastasis. The purpose of this study was first to determine whether an imbalance between MMP-9 and E-cadherin expression correlates with metastasis from human transitional cell carcinoma (TCC) of the bladder after therapy with neoadjuvant chemotherapy and radical cystectomy and then to determine whether treatment of human TCC xenografts growing in nude mice with interferon (IFN)-alpha would restore this balance, thereby limiting tumor invasion and metastasis. We used in situ hybridization to evaluate the expression of several metastasis-related genes, including MMP-9 and E-cadherin, in paraffin-embedded biopsy specimens from 55 patients with muscle-invasive TCC treated with neoadjuvant methotrexate, vinblastine, doxorubicin, and cisplatin chemotherapy and radical cystectomy. By multivariate analysis, an MMP-9:E-cadherin ratio of >1.8 was an independent prognostic factor for disease progression. In vitro incubation of an IFN-resistant, highly metastatic human TCC cell line, 253J B-V(R) with noncytostatic concentrations of IFN-alpha down-regulated the activity of MMP-9, up-regulated E-cadherin, and inhibited in vitro invasion. 253J B-V(R) cells were implanted into the bladders of athymic nude mice. Systemic therapy with IFN-alpha (10,000 units s.c. daily) decreased the expression of MMP-9, increased expression of E-cadherin, reduced tumor volume, and inhibited metastasis. The MMP-9:E-cadherin ratio was 4.5 in untreated controls and 1.1 after IFN-alpha treatment. Moreover, systemic low-dose daily IFN-alpha potentiated the efficacy of paclitaxel. These studies indicate that in addition to its antiproliferative and antiangiogenic effects, IFN-alpha limits tumor invasion by restoring the normal balance between MMP-9 and E-cadherin and enhances the activity of systemic chemotherapy.

Expression of interleukin-8 correlates with angiogenesis, tumorigenicity, and metastasis of human prostate cancer cells implanted orthotopically in nude mice.

We determined whether the expression of interleukin-8 (IL-8) by human prostate cancer cells correlates with induction of angiogenesis, tumorigenicity, and production of metastasis. Low and high IL-8-producing clones were isolated from the heterogeneous PC-3 human prostate cancer cell line. The secretion of IL-8 protein correlated with transcriptional activity and levels of IL-8 mRNA. All PC-3 cells expressed both IL-8 receptors, CXCR1 and CXCR2. The low and high IL-8-producing clones were injected into the prostate of nude mice. Titration studies indicated that PC-3 cells expressing high levels of IL-8 were highly tumorigenic, producing rapidly growing, highly vascularized prostate tumors with and a 100% incidence of lymph node metastasis. Low IL-8-expressing PC-3 cells were less tumorigenic, producing slower growing and less vascularized primary tumors and a significantly lower incidence of metastasis. In situ hybridization (ISH) analysis of the tumors for expression of genes that regulate angiogenesis and metastasis showed that the expression level of IL-8, matrix metalloproteinases, vascular endothelial growth factor (VEGF), and E-cadherin corresponded with microvascular density and biological behavior of the prostate cancers in nude mice. Collectively, the data show that the expression level of IL-8 in human prostate cancer cells is associated with angiogenesis, tumorigenicity, and metastasis.

Paraneoplastic pemphigus sera react strongly with multiple epitopes on the various regions of envoplakin and periplakin, except for the c-terminal homologous domain of periplakin.

Paraneoplastic pemphigus sera react with multiple plakin family proteins, among which only envoplakin and periplakin are constantly detected by immunoblotting using normal human epidermal extracts. Using bacterial expression vectors containing polymerase chain reaction-amplified cDNA, we have prepared variously truncated recombinant glutathione-S-transferase-fusion proteins of envoplakin and periplakin, which presented N-terminal, central and C-terminal domains of each protein, as well as the so-called C-terminal homologous domain of envoplakin and the junctional regions of these domains. By immunoblotting using these 11 recombinant proteins, we demonstrated that most of the 26 paraneoplastic pemphigus sera reacted very strongly with multiple recombinant proteins of envoplakin and periplakin, except for the C-terminal homologous domain of periplakin. We also examined the reactivity with these recombinant proteins of other blistering diseases, including pemphigus vulgaris, pemphigus foliaceus, and bullous pemphigoid, and found that a few nonparaneoplastic pemphigus sera showed a weak reactivity with some of the recombinant proteins. Interestingly, some sera showed relatively strong reactivity with the C-terminal homologous domain of periplakin to which paraneoplastic pemphigus sera reacted less frequently. These results indicate that, although nonparaneoplastic pemphigus sera occasionally show a weak reactivity with envoplakin and periplakin, the pathogenicity and the mechanism of antibody production in these cases may be different from those in paraneoplastic pemphigus.

Specific somatostatin receptors on human pituitary adenoma cell membranes.

Specific somatostatin (SRIH) receptors on human pituitary adenoma cell membranes were characterized using [125I]Tyr11-SRIH as the radioligand. Specific binding of [125I] Tyr11-SRIH to adenoma cell membranes reached a steady state within 30 min at 25 C, and semilogarithmic analysis of the data revealed that the rate of the binding was linear at 25 C with a t1/2 of 13.2 min. Specific binding increased linearly with 5-160 micrograms plasma membrane protein. SRIH-14 and SRIH-28 inhibited [125I]Tyr11-SRIH binding to adenoma cell membranes with ID50S of 0.32 and 0.50 nM, respectively, while secretin, glucagon, gastrin, cholecystokinin-8, bombesin, TRH, LHRH, human GH-releasing factor-(1-44)-NH2, D-Ala2-met-enkephalin, gamma-aminobutyric acid and taurine did not significantly inhibit binding. All of 13 GH-secreting adenomas investigated had specific and high affinity SRIH receptors, with a dissociation constant (Kd) of 0.80 +/- 0.15 nM (mean +/- SEM) and a maximal binding capacity (Bmax) of 234.2 +/- 86.9 fmol/mg protein (mean +/- SEM). Among five of the nonsecreting pituitary adenomas examined, two had SRIH receptors with Kd values of 0.18 and 0.32 nM and Bmax values of 17.2 and 48.0 fmol/mg protein, respectively. In the remaining three, SRIH receptors were not detected. These results indicate that GH-secreting adenomas as well as some nonfunctioning adenomas have specific SRIH receptors, and hence, the function of the adenomas could be altered by SRIH.

Effects of vasopressin on smooth muscle cells of guinea-pig mesenteric vessels.

1 The effects of vasopressin on the membrane and contractile properties of smooth muscle cells of guinea-pig mesenteric arteries, and mesenteric and portal veins were investigated in various ionic environments by means of a micro-electrode technique and an isometric tension recording method. The results were compared with those obtained with oxytocin and noradrenaline (NA).2 In the mesenteric jejunal artery, the mean membrane potential was -56.6 +/- 2.3 mV, s.d, and the membrane was electrically quiescent. Application of outward current pulses generated small graded responses, and the current voltage relationship was linear with application of an inward current pulse.3 Vasopressin and NA depolarized the membrane and increased the membrane resistance. Vasopressin was a 1000 times more potent than oxytocin in depolarizing the membrane. In high concentrations, vasopressin (1 x 10(-3) or 1 x 10(-2) iu/ml) or NA (5.9 x 10(-5) M) generated slow oscillatory membrane potential changes (slow waves) and spikes during the depolarization. The excitatory actions of vasopressin and NA were not suppressed by tetrodotoxin (3.1 x 10(-7) M) or ouabain (1.3 x 10(-6) M) and the actions of vasopressin were not suppressed by adrenoceptor blocking agents (3.9 x 10(-7) M phentolamine or 3.6 x 10(-7) M propranolol).4 The depolarization induced by vasopressin or NA is mainly due to a decrease in the K-permeability of the membrane. However, the contribution of other ionic species to the depolarization induced by vasopressin or NA differed, e.g. in low concentrations of [Na](o), the NA-induced depolarization was suppressed to a greater extent than that due to vasopressin. In low concentrations of [Ca](o), the vasopressin-induced depolarization was suppressed to a greater extent than with NA.5 In low concentrations of [Ca](o) and in the presence of vasopressin or NA, spike generation was inhibited but slow waves were not. In low concentrations of [Na](o), the vasopressin-induced slow waves and spikes were for the great part preserved, but with a high concentration of [Ca](o), vasopressing-induced slow waves were suppressed.6 Both vasopressin and NA produced contractions in the jejunal mesenteric artery. However, the maximum contraction in response to vasopressin was larger than that to NA, although both induced similar membrane depolarization. In a low concentration of [Na](o), vasopressin but not NA produced a contraction.7 In the cranial mesenteric artery, NA (5.9 x 10(-5) M) depolarized the membrane and produced a contraction, while vasopressin (1 x 10(-1) iu/ml) and oxytocin (1 x 10(-1) iu/ml) neither depolarized the member nor produced a contraction. In the mesenteric vein, NA (5.9 x 10(-5) M) slightly depolarized the membrane and produced a small contraction. On the other hand, in the portal vein, NA (5.9 x 10(-7) M) produced a marked depolarization and a contraction. Vasopressin (1 x 10(-1) iu/ml) and oxytocin (1 x 10(-1) iu/ml) produced neither excitatory nor inhibitory actions in these veins.8 It is concluded that vasopressin acts on only small muscular arteries, while NA acts on all mesenteric vessels, particularly the portal vein. Therefore, the hepatic portal vascular resistance may be increased by NA and reduced by vasopressin.

Isoprenaline- and noradrenaline-induced hyperpolarization of guinea-pig liver cells.

1 Effects of pretreatment with isoprenaline (Isop) or noradrenaline (NA) and various ionic environments on the NA-induced or Isop-induced hyperpolarization of guinea-pig liver cells were investigated by means of a microelectrode technique.2 NA (5.9 x 10(-6) M) decreased the membrane resistance, and hyperpolarized the membrane with or without generation of an initial transient small depolarization. The NA-induced initial depolarization was not dependent on the membrane potential and was increased by Isop (4.0 x 10(-6) M) or glucagon (10(-7) M).3 In Ca-free solution, the NA-induced hyperpolarization became transient and a continuous depolarization followed in the presence of NA. Repetitive application of NA resulted in a complete disappearance of the NA-induced hyperpolarization and was replaced by a slowly developing depolarization with or without generation of the initial transient depolarization. In excess [Ca](o), the NA or Isop-induced hyperpolarization was increased.4 Both Isop and glucagon hyperpolarized the membrane and decreased the membrane resistance, to various degrees. Repetitive application of Isop or glucagon resulted in the disappearance of both Isop and glucagon-induced hyperpolarizations. Pretreatment with NA not only resulted in a recovery of both Isop and glucagon-induced hyperpolarizations, but also extensively enhanced the hyperpolarization.5 After pretreatment with Isop, the NA-induced hyperpolarization was decreased in amplitude and duration and was followed by a slowly developing depolarization. After repetitive application of Isop, NA produced only depolarization of the membrane, and in these conditions, Isop, glucagon or ATP also depolarized the membrane. These depolarizations were reversed to hyperpolarizations by pretreatment with excess [Ca](o).6 After treatment with Na-deficient solution, NA depolarized the membrane and decreased the membrane resistance. Excess [Ca](o) restored the NA-induced membrane response from one of depolarization to one of hyperpolarization.7 In the presence of tetraethylammonium 10mM, the NA-induced hyperpolarization became transient or ceased and depolarization occurred with a reduction in the membrane resistance.8 It is postulated that both NA and Isop increase the free [Ca](i) by releasing bound Ca from storage sites and consequently an increase in K conductance follows. NA but not Isop promotes Ca-influx which replenishes the storage site. In Ca-depleted conditions, NA does not elevate the free [Ca](i) to a threshold concentration required for hyperpolarization, probably because NA induces a small release of Ca from storage sites.

Actions of nitroglycerine on smooth muscles of the guinea-pig and rat portal veins.

1 Effects of nitroglycerine (NG) on the electrical and mechanical activities of smooth muscle cells of the rat and guinea-pig portal veins were studied by a microelectrode technique and an isometric tension recording method.2 The membrane potentials of smooth muscle cells in the rat and guinea-pig were -44.4 mV and -47.6 mV, respectively. In both species the smooth muscle cells generated spikes as burst discharges.3 In the guinea-pig portal vein, NG (2.8 x 10(-8) M) produced biphasic potential changes, an initial transient hyperpolarization followed by depolarization. The hyperpolarization suppressed and depolarization enhanced spike activities.4 From the changes in the membrane potential produced by NG in various concentrations of [K](o), [Na](o) or [Ca](o), it is postulated that the hyperpolarization is due to an increase in the K-permeability and the depolarization is due to an increase in the Na-permeability of the membrane.5 NG (2.8 x 10(-5) M) had no effect on the membrane activity of the rat portal vein.6 NG consistently suppressed mechanical activities generated in both tissues. The minimum concentration required to suppress the mechanical activity was lower in the guinea-pig than in the rat portal vein.7 NG suppressed the contraction due to noradrenaline more than that evoked by excess [K](o) in both species.8 From these experiments, it is concluded that NG relaxes the muscular bed of portal veins of both species. In the rat portal vein, suppression of mechanical activity had no causal relation to the membrane activity. In contrast, in the guinea-pig portal vein, suppression of mechanical activity was slightly modified by changes in the membrane activity, i.e. hyperpolarization additively contributes to the relaxation and depolarization slightly suppresses the relaxation.

Electrical properties of smooth muscle cell membrane and neuromuscular transmission in the guinea-pig basilar artery.

1 The membrane properties of smooth muscle cells and neuromuscular transmission in the guinea-pig basilar artery were investigated by use of microelectrodes.2 The membrane potential was -47.0 mV and the muscle tissue possessed cable-like properties as determined by the current-voltage relationships. The mean value of the spacè constant was 0.78 mm.3 An outward current produced a graded response and, in some cases, spike generation. This membrane response was enhanced in the presence of tetraethylammonium (TEA, 5 mM), and an increased concentration of TEA (10 mM) generated spontaneous spikes in most of the cells. Action potentials induced by TEA were abolished in the presence of MnCl(2) (5 mM) but not by isoprenaline (4 x 10(-6) M).4 Acetylcholine (ACh), over 10(-7) M, hyperpolarized the membrane and decreased the membrane resistance. This hyperpolarization increased in the presence of low [K](o) (below 5.9 mM), but decreased in [K](o) concentrations over 17.8 mM. Pretreatment with atropine (10(-6) M) suppressed the ACh-induced hyperpolarization. Therefore, this action of ACh is due to an increase in the K-conductance of the membrane produced by activation of the muscarinic receptors.5 Noradrenaline in concentrations up to 10(-4) M did not modify the membrane potential and resistance, while 10(-5) M, histamine, 5-hydroxytryptamine and adenosine triphosphate (ATP) depolarized the membrane. The depolarization induced by histamine or ATP was suppressed by reducing [Na](o). The histamine-induced depolarization was accompanied by an increase and the ATP-induced one by a decrease in the membrane resistance. The action of histamine was suppressed by treatment with H(1)- but not H(2)-receptor blocking agents (dephenhydramine and cimetidine, respectively).6 Perivascular nerve stimulation (0.2 ms pulse duration) evoked excitatory junction potentials (e.j.ps). An increase in the number and frequency of stimuli enhanced the e.j.p. amplitude. In the presence of 1 mM TEA, a spike was evoked on the e.j.ps. A very high concentration of phentolamine (3.6 x 10(-4) M) or the usual concentration of tetrodotoxin (10(-7) M) abolished the generation of e.j.ps. Spontaneously generated miniature e.j.ps were never recorded from the resting membrane.7 The results are discussed in relation to regional specificities of smooth muscle cells of cerebral arteries in the guinea-pig.