OPC-13340, a new dihydropyridine calcium channel blocker attenuates rapid vascular smooth muscle cell growth in spontaneously hypertensive rats

We investigated the mechanism of the antimitotic effects of calcium channel blockers in vascular smooth muscle cells (VSMC) from spontaneously hypertensive rats (SHR). VSMC from SHR exhibited rapid proliferation through a quick transition from the G0/G1 to the DNA synthetic (S) phase and from the S to the G2/mitotic (M) phase, whereas the DNA synthetic rate itself was equal to that of Wistar-Kyoto rats (WKY). OPC-13340, a new dihydropyridine calcium channel blocker, dose-dependently decreased incorporation of [3H]thymidine into the DNA fragments in randomly cycling VSMC in SHR. Cell cycle analysis showed that the rapid transition from the S to the G2/M period was restored by OPC-13340 to the control level in WKY, whereas the quick transition from G0/G1 to S was unaffected. This antimitotic effect of OPC-13340 was reflected by attenuation of enhanced cellular protein synthesis during the G2/M period. Protein synthesis in the G0/G1 period was not influenced by OPC-13340. Thus, these data indicate that the calcium channel blocker OPC-13340 mitigates the enhanced proliferation observed in randomly cycling VSMC from SHR and that this effect is primarily due to normalization of the premature mitosis during the G2/M period.

[Management of type A acute aortic dissection--results of the cases with thrombosed false lumen]

By reviewing the outcome, we studied the propriety of our principles for the treatment of type A acute aortic dissection in 45 patients, encountered during the 10-year period between 1981 and 1990. We conducted a comparative study of patients with a thrombosed false lumen (type T) and a patent false lumen (type P) to examine the effect of an acutely thrombosed false lumen on the prognosis of this disease. For the 25 patients treated in the first 6 years (1981-1986), operation was performed as soon as exact diagnosis was made, regardless of the presence of complications and the type or severity of the disease. Early death occurred in 9/20 operated cases and in 4/5 unoperated cases, so 13/25 patients died for a 52.0% mortality rate. For the 20 patients who received treatment in the latter period (1987-1990), we gave priority to conservative treatment for type T cases that were free from complications, and adopted a treatment method attaching greater importance to the resection of intimal tears. As a results, early deaths were observed in only 4 type P patients (20.0%) who underwent operation, a significant better result (p < 0.05). For patients in whom we were able to excise the intimal tear (30.0%, early mortality rate), the results were better than in those in whom the intimal tear were left alone (53.8%). The results were particularly good in type T patients (25.0% of them underwent intimal tear resection and 71.4% underwent no operation for the intimal tear).(ABSTRACT TRUNCATED AT 250 WORDS)

Mapping of the cochlear nucleus subregions in the rat with neuronal Fos protein induced by acoustic stimulation with low tones

To explore the mode of appearance of Fos, a gene product of proto-oncogene c-fos, in the cochlear nucleus, a pure tone was given to rats and Fos was detected by immunohistochemistry. Following low-tone stimuli applied with moderate ranges of sound intensity, neurons with Fos-label occurred band-like in the ventral subregions of the dorsal cochlear nucleus. Organization of low-to-high tones in the ventral-to-dorsal orientation became visible at the caudal level. Several other subnuclei consistently exhibited Fos with no topographic pattern. Neurons interspersed in the adjoining vestibulocochlear nerve were also found to elicit Fos. Low-tone stimuli with very high sound intensity led to a rather widespread distribution of Fos, making the tone-specific distribution less visible.

Plasma adenosine concentrations are elevated in conscious spontaneously hypertensive rats

1. Plasma levels of adenosine were measured in unrestrained, conscious spontaneously hypertensive rats (SHR) to examine the potential role of adenosine, a naturally occurring substance with profound cardiovascular actions, in cardiovascular regulation in these genetically hypertensive rats. 2. We employed a specific and sensitive assay for adenosine based on fluorescent determination of adenine compounds by high performance liquid chromatography. 3. Plasma adenosine concentrations were significantly higher in 13 week old SHR with hypertension than in Wistar-Kyoto rats (0.165 +/- 0.022 vs 0.096 +/- 0.008 mumol/L; P less than 0.05). 4. These observations indicate that plasma adenosine levels are increased in conscious SHR with established hypertension, and also suggest that adenosine may be at least partly involved in the pathophysiology of high blood pressure in SHR.

[Efficacy of nicorandil on myocardial protection during coronary artery bypass grafting--a comparison with diltiazem]

Diltiazem (DTZ), a calcium slow channel blocker, is estimated to be highly effective for myocardial protection and the prevention of perioperative coronary spasms (PCS). However, the use of high doses of DTZ sometimes results in difficulty in coming off cardiopulmonary bypass due to negative chronotropic activity. Nicorandil (NCD) has remarkable coronary vasodilating effect but possesses little negative chronotropic activity. The purpose of this study was to compare NCD with DTZ with respect to effect on myocardial protection during coronary artery bypass grafting (CABG). As parameters, excess lactate (delta XL), redox potential (delta Eh), left and right ventricular stroke work indices (LVSWI, RVSWI), cardiac index (C.I.), systemic vascular resistance index (SVRI.), myocardial isoenzymes (CK-MB, LDH1), number of PCS and recovery time of chronotropic action were used. delta XL, delta Eh, LVSWI, RVSWI, C.I., SVRI, CK-MB, LDH1 were measured at 0, 1, 3, 6, 9, 18 and 24 hours after the removal of aortic cross clamping. The degree of chronotropic action was evaluated by the length of the recovery time to self beat or normal sinus rhythm after the removal of aortic cross clamping. Forty patients who underwent CABG with retrograde cold blood cardioplegia between Dec. 1989 and May 1991 were divided into the NCD group (n = 20), in which 1.1 micrograms/kg/min NCD was continuously administered from the beginning of the operation and the DTZ group (n = 20), in which the initial St. Thomas cardioplegia containing 5 mg/L and subsequent cold blood cardioplegia solution contained DTZ 3.5 mg/L, for a total DTZ dose of less than 10 mg.(ABSTRACT TRUNCATED AT 250 WORDS)

New method of detecting nitric oxide production

Nitric oxide (NO) reacts with H2O2 to produce a rise in potent luminol-dependent chemiluminescence under neutral pH conditions. We applied this reaction to the continuous detection of NO released from the rat isolated perfused kidney with simultaneous pressure changes. Acetylcholine increased NO release dose-dependently with the pressure reduction. An NO synthesis inhibitor, NG-monomethyl-L-arginine, abolished the release. This inhibition was reversed by the addition of L-arginine.

[Clinical study of terodiline hydrochloride for the treatment of urinary frequency and urinary incontinence, and its cardiovascular adverse effects]

We evaluated the effectiveness and side effects of terodiline hydrochloride in 109 patients with urinary frequency and urinary incontinence. The drug was administered at a dose of 24 mg once a day or 12 mg twice a day for 4 weeks. Symptoms such as urinary frequency and urinary incontinence were alleviated in 101 out of 109 patients (92.7%). Mild side effects such as thirst, dysuria, sense of residual urine, orthostatic hypotension and arrhythmia were observed in 9 out of 109 patients (8.2%). Side effects such as orthostatic hypotension and arrhythmia were observed on the 28th day or the 20th day of the administration, but these symptoms disappeared with discontinued use of this medicine. The results obtained from this study suggest that terodiline hydrochloride may be greatly useful for the patients with urinary frequency and urinary incontinence. But we must take account of the side effects such as orthostatic hypotension and arrhythmia.

[Ischemic cardiomyopathy associated with ischemic mitral regurgitation--a case report of successful repair]

We experienced a case of 62-year-old man with ischemic cardiomyopathy and mitral regurgitation. He had a heart failure of New York Heart Association class IV together with unstable angina. His further examination showed an enlarged left ventricle with markedly reduced ejection fraction (12.9%) and ischemic mitral regurgitation of grade III associated with 3-vessel disease. He underwent three coronary artery bypass graftings and mitral annuloplasty by a modification of Kay's method. He showed a remarkable improvement of heart failure and cardiac function together with a disappearance of mitral regurgitation. He discharged from hospital in NYHA class II on the 50th postoperative day and lives an almost normal life now. Operative indication and management of ischemic cardiomyopathy and mitral regurgitation were discussed.

Distribution and cerebellar projections of cholinergic and corticotropin-releasing factor-containing neurons in the caudal vestibular nuclear complex and adjacent brainstem structures

By using immunohistochemistry combined with lesioning and retrograde neuronal labeling techniques, cholinergic neurons and corticotropin-releasing factor-immunoreactive neurons were examined for their distribution, coincidence and cerebellar projections in feline vestibular nuclear complex and adjacent brainstem structures. Cholinergic neurons as revealed here with choline acetyltransferase immunoreactivity were found massively in the abducens and hypoglossal nuclei, dorsal motor nucleus of the vagus nerve and nucleus of Roller; less numerously in the medial vestibular, prepositus hypoglossi and solitary nuclei and the caudal two-thirds of descending vestibular nucleus; and only occasionally in the intercalated and supravestibular nuclei and cell groups f, x and z. Corticotropin-releasing factor-immunoreactive neurons were found clustered in the prepositus hypoglossi nucleus and also in cell groups f and x and the rostral two-thirds of descending vestibular nucleus, less numerously in the medial vestibular, intercalated and solitary nuclei and nucleus of Roller, and only occasionally in the caudal one-third of descending vestibular nucleus, the dorsal motor nucleus of the vagus nerve, supravestibular nucleus and cell group z. The lateral and superior vestibular nuclei did not contain either type of neuron. The two types of immunopositive neurons observed in most of the brainstem nuclei differed in cell size, distribution-pattern and rostrocaudal level of occurrence. While there were many regions which exhibited both types of immunopositive neurons, perikarya colocalizing the cholinergic and peptide markers were not detected in the brainstem. Following unilateral, partial lesioning of the vestibular nuclear complex, corticotropin-releasing factor-immunoreactive mossy fiber terminals (rosettes) disappeared from the ipsilateral flocculus. However, such lesions did not produce clear-cut changes of cholinergic terminals in the vermis. Following retrograde neuronal labeling combined with immunohistochemistry, the two types of immunopositive neurons observed in most of the brainstem sites were found to project to the vermal lobules I-III, IX and X. On comparison of these immunopositive projection neurons with non-immunoreactive, retrogradely labeled neurons, the cholinergic neurons and the peptide-immunoreactive neurons were found to constitute a major part of the total vestibulocerebellar neuronal population. The results indicate chemical heterogeneity in vestibular nuclear complex and cerebellar afferents.

Sliding velocity of isolated rabbit cardiac myosin correlates with isozyme distribution

To investigate the relationship between the mechanical and biochemical properties of cardiac myosin, the sliding velocity of isolated cardiac myosin obtained from both euthyroid and hyperthyroid rabbits on actin cables was measured with an in vitro motility assay system. Ten rabbits (T) were treated with L-thyroxine to induce hyperthyroidism, and eight nontreated animals (N) were used as controls. Myosin was purified from the left ventricles of anesthetized animals. Myosin isozyme content was analyzed by the pyrophosphate gel electrophoresis method, and myosin adenosinetriphosphatase (ATPase) activity was determined on the same sample. Long well-organized actin cables of green algae, Nitellopsis, were used in the in vitro motility assay. Small latex beads were coated with purified cardiac myosin and introduced onto the Nitellopsis actin cables. Active unidirectional movement of the beads on the actin cables was observed under a photomicroscope, and the velocity was measured. The velocity was dependent on ATP concentrations, and the optimal pH for bead movement was approximately 7.0-7.5. The mean velocity was higher in T than in N (0.66 +/- 0.12 vs. 0.32 +/- 0.09 micron/s, P less than 0.01). Both Ca(2+)-activated ATPase activity and the percentage of alpha-myosin heavy chain were also higher in T than in N (0.691 +/- 0.072 vs. 0.335 +/- 0.072 microM Pi.mg-1.min-1, P less than 0.01, and 79 +/- 12 vs. 26 +/- 7%, P less than 0.01, respectively). The velocity of myosin closely correlated with both Ca(+2)-activated myosin ATPase activity (r = 0.87, P less than 0.01) and the percentage of alpha-myosin heavy chain (r = 0.87, P less than 0.01).

Inhibition of hepatic metastasis of colon carcinoma by asialo GM1--positive cells in the liver

This study investigates the role of hepatic asialo GM1-positive cells in inhibiting hepatic metastasis of colon carcinoma (colon adenocarcinoma 38) in mice after administration of a biological response modifier, streptococcal derivative (OK432). Administration of OK432 increased the number of asialo GM1-positive cells in the liver, enhanced natural killer activity of hepatic mononuclear cells and reduced the number of hepatic metastases of colon carcinoma inoculated into the superior mesenteric vein. Administration of antiserum against asialo GM1 reduced the number of hepatic asialo GM1-positive cells, abolished natural killer activity of hepatic mononuclear cells and increased the number of hepatic metastases. In addition, administration of antiserum against asialo GM1 even after OK432 treatment also decreased the number of asialo GM1-positive cells, reduced natural killer activity of hepatic mononuclear cells and increased the number of hepatic metastases of colon carcinoma. However, administration of gadolinium chloride, which suppresses phagocytic function of Kupffer cells, did not influence the natural killer activity of hepatic mononuclear cells or the number of hepatic metastases. In vivo tumor-neutralization assay revealed that tumor growth was inhibited by the hepatic mononuclear asialo GM1-positive cells, but not by T lymphocytes or Kupffer cells after OK432 administration. These results suggest that an increased number of hepatic asialo GM1-positive cells after administration of OK432 plays an important role in protecting against metastasis of colon carcinoma in the liver.

Role of cellular superoxide dismutase against reactive oxygen metabolite injury in cultured bovine aortic endothelial cells

We examined the protective effect of cellular superoxide dismutase against extracellular hydrogen peroxide in cultured bovine aortic endothelial cells. 51Cr-labeled cells were exposed to hydrogen peroxide generated by glucose oxidase/glucose. Glucose oxidase caused a dose-dependent increase of 51Cr release. Pretreatment with diethyldithiocarbamate enhanced injury induced by glucose oxidase, corresponding with the degree of inhibition of endogenous superoxide dismutase activity. Inhibition of cellular superoxide dismutase by diethyldithiocarbamate was not associated either with alteration of other antioxidant defenses or with potentiation of nonoxidant injury. Enhanced glucose oxidase damage by diethyldithiocarbamate was prevented by chelating cellular iron. Inhibition of cellular xanthine oxidase neither prevented lysis by hydrogen peroxide nor diminished enhanced susceptibility by diethyldithiocarbamate. These results suggest that, in cultured endothelial cells: 1) cellular superoxide is involved in mediating hydrogen peroxide-induced damage; 2) superoxide, which would be generated upon exposure to excess hydrogen peroxide independently of cellular xanthine oxidase, promotes the Haber-Weiss reaction by initiating reduction of stored iron (Fe3+) to Fe2+; 3) cellular iron catalyzes the production of a more toxic species from these two oxygen metabolites; 4) cellular superoxide dismutase plays a critical role in preventing hydrogen peroxide damage by scavenging superoxide and consequently by inhibiting the generation of the toxic species.

Second messenger signaling in the regulation of cytosolic pH and DNA synthesis by parathyroid hormone (PTH) and PTH-related peptide in osteoblastic osteosarcoma cells: role of Na+/H+ exchange

The present study was performed to investigate the regulation of cytosolic pH (pHi) and DNA synthesis by parathyroid hormone(PTH) and PTH-related peptide (PTHrP) in osteoblasts, using osteoblastic osteosarcoma cells, UMR-106 which possessed PTH-responsive dual signal transduction systems (cAMP-dependent protein kinase (PKA) and calcium/protein kinase C [Ca/PKC]) and amiloride-inhibitable Na+/H+ exchange system. Both human (h)PTH-(1-34) and hPTHrP-(1-34) caused a progressive decrease in pHi and the inhibition of [3H]thymidine incorporation (TdR) to the same degree in a dose-dependent manner with a minimal effective dose of 10(-10) M. Dibutyryl cAMP (10(-4) M and Sp-cAMPS (10(-4) M), a direct stimulator of PKA also caused a progressive decrease in pHi, and calcium ionophores (A23187 and ionomycin, 10(-6) M) caused a transient decrease in pHi. Pretreatment with amiloride (0.3 mM) mostly blocked dbcAMP- and Sp-cAMPS-induced decrease in pHi but did not affect calcium ionophore-induced decrease in pHi. In the presence of amiloride, PTH and PTHrP caused a transient decrease in pHi, which was similar to the pattern of calcium ionophore-induced change in pHi. Amiloride did not affect the inhibition of TdR by PTH or PTHrP as well as that by cAMP analogues or calcium ionophores. The present study indicated that PTH and PTHrP caused cytosolic acidification through PKA-inhibited Na+/H+ exchange and increased cytosolic calcium-induced pathway and that the regulation of DNA synthesis by PTH and PTHrP was not via Na+/H+ exchange system.

[A case of acute renal failure in a patient with idiopathic hypouricemia]

This report is a 17-year-old man with an acute renal failure who complained of nausea, vomiting, bilateral loin pain and abdominal pain after scuffle. Renal biopsy specimen obtained from the left kidney revealed acute tubular necrosis. After recovering renal function he showed extreme hypouricemia (serum uric acid, 0.6 mg/dl) and elevated uric acid clearance (62-78 ml/min). The fractional excretion of uric acid (CUA/Ccr) could not be influenced by either oral pyrazinamide or probenecid. As no other renal tubular or metabolic abnormalities were detected, it is suggested that presecretory reabsorption defect or subtotal defect in uric acid transportation was responsible for the hypouricemia in this patient.

[Measurement of renal plasma flow and glomerular filtration rates in diabetic subjects]

To clarify the problem in the measurement of renal plasma flow and glomerular filtration rates in diabetes, the effect of glucose on the determination of para-aminohippuric acid (PAH) and inulin was examined. The concentration of urinary PAH in glucosuric diabetic subjects decreased after the storage of urine samples because of the glycation of PAH. Therefore, glucose must be removed by the acid treatment before the determination of the concentrations of urinary PAH. Since glucose can interfere with the assay of inulin, the sample must be treated with NaOH prior to the determination of the inulin concentration. GFR of the subjects with type 2 diabetes was next examined. GFR in the subjects with a duration of diabetes less than 10 years was significantly higher than that in the subjects with a duration of diabetes more than 10 years. Thus, the subjects with short-term type 2 diabetes may present with hyperfiltration similar to the subjects with short-term type 1 diabetes.

[Surgical treatment of active infective endocarditis and prosthetic valve endocarditis]

Fifteen patients with active native valve endocarditis (NVE) and 5 with prosthetic valve endocarditis (PVE) were subjected to this study. Among the patients with NVE, one of 10 with simple destruction of leaflets and 2 of 5 with annular infection died postoperatively of cerebral bleeding and persistent infection. Five patients with annular infection, whose microorganisms were Streptococcus faecalis, Staphylococcus epidermidis and gram-negative coccus, had a shorter duration from onset to operation (mean 38 days) compared with the others (mean 85 days). A patient with NVE requires an urgent operation, especially when these microorganisms are identified. Among those with PVE, 3 underwent operation at the active phase and one at the chronic phase. Two patients with mechanical valve endocarditis by Staphylococcus and Candida died, but the other 2 with bioprosthetic valve endocarditis by alpha-Streptococcus survived, because infection was localized in the leaflets. Another patient with mechanical valve endocarditis by alpha-Streptococcus survived with conservative management. While a patient with bioprosthetic valve endocarditis requires an early operation as well as NVE, a patient with mechanical valve endocarditis requires selected management considering the microorganism and general condition.

Noninvasive assessment of cardiomyopathy development with simultaneous measurement of topical 1H- and 31P-magnetic resonance spectroscopy

Background. It might be possible to estimate the metabolic derangement of cardiac muscle by topical nuclear magnetic resonance spectroscopy (MRS) in vivo without killing the animal. Methods and Results. By use of topical 1H- and 31P-MRS focused on the heart of Syrian hamsters with or without cardiomyopathy (CM; BIO 14.6 strain), the chemical constituents were measured in vivo nondestructively and repetitively at several stages of development of CM. A phantom experiment and two-dimensional plot of chain methylenes (CH2) of lipid/water ratio by 1H-MRS versus creatine phosphate (CP)/[beta-P]ATP ratio by 31P-MRS indicated that signal cross talk from the adjacent organs was negligible. Even before the onset of clinical or pathological manifestation of CM (7 weeks after birth), CH2/water ratio by 1H-MRS was lower in the CM group (7.3 +/- 0.7%) than in control (11.8 +/- 2.0%, p less than 0.05), and it decreased further at the hypertrophic stage (17 weeks, 4.1 +/- 0.7%, p less than 0.05) and the congestive stage (27 weeks, 4.3 +/- 0.9%, p less than 0.05). In contrast, the CP/[beta-P]ATP ratio by 31P-MRS started to decrease at the hypertrophic stage (1.90 +/- 0.18 versus 2.52 +/- 0.24, p less than 0.05) and decreased further at the congestive stage to 1.53 +/- 0.18 (p less than 0.01). These in vivo MRS data were confirmed by both biochemical assay and in vitro MRS analysis in heavy water after the animals were killed. Conclusions. A combination of topical 1H-MRS and 31P-MRS in vivo is promising for the noninvasive and sensitive assessment of cardiac muscle metabolism. Comparison of these MRS studies and biochemical analysis suggested not only the modification of water, lipid, CP, or ATP contents but also the reduction of flexibility or fluidity of lipids in cardiomyopathic heart.

[Surgical treatment of native valve endocarditis]

Twenty eight patients with native valve endocarditis (NVE) were subjected to this study. Thirteen patients underwent an operation at the chronic phase, and 15 patients at the active phase. One of the 13 patients at the chronic phase died of cardiac rupture due to myocardial infarction which had occurred preoperatively, and one of 10 patients at active phase without annular infection died of rupture of mycotic cerebral aneurysm early postoperatively. Among 5 patients at the active phase with annular infection, prosthetic valve endocarditis occurred in one patient 1.5 months after supraannular aortic valve replacement, and the second operation with a translocation technique was needed. This patient was lost from low output syndrome. Another patient in this group, who underwent a translocation technique because of mycotic annular abscess, died of intestinal infarction late postoperatively. The other 24 patients went a good postoperative course. Five patients with annular infection at the active phase had a shorter duration from the infectious onset to operation (20 days to 2 months, average 38 days), and the causative microorganisms were streptococcus faecalis, staphylococcus epidermidis and gram-negative coccus. One patient, who died of mycotic cerebral aneurysmal rupture, had candida albicans as a causative microorganism. For patients with NVE, an early aggressive operation is essential before infection extends to the annulus or to other vital organs, especially when these microorganisms are identified.

Severe hypoxia due to ventilation-perfusion mismatch caused by aortic arch aneurysm

We report a very rare case of hugh aortic arch aneurysm associated with aortic restenosis, which caused severe hypoxia due to ventilation-perfusion mismatch by compression of the left main bronchus and the right pulmonary artery. Aortic arch replacement was performed under circulatory arrest and deep hypothermia in addition to aortic valve replacement as a redo operation, and consequently such hypoxia was relieved.

[Coronary artery bypass grafting in patients with poor left ventricular function using retrograde continuous cold blood cardioplegia]

Patients with poor left ventricular function or those requiring urgent surgery may have more extensive ischemic myocardial injury if myocardial preservation is incomplete. We have performed coronary artery bypass grafting (CABG) aimed at complete revascularization in such cases using RC-CBCP, which is considered more effective on myocardial preservation during aortic cross-clamping in particular to protect ischemic area distal to severe coronary artery stenosis or obstruction. In the present study, in 25 patients with poor left ventricular function (left ventricular ejection fraction; LVEF less than or equal to 0.3) including 10 patients who required urgent surgery, the operative results were evaluated. All the distal and proximal anastomoses of grafts (average 2.5 grafts) were completed during one aortic cross-clamping using RC-CBCP, therefore graft flow was obtained immediately after release of the aortic clamping. Though this method required 142 minutes of a mean aortic cross-clamping time, myocardial protection was considered to be preferable judging from postoperative isoenzymatic evaluation and improved ventricular function. Fifteen patients with elective CABG were all alive and restored to NYHA class I to II. Among 10 patients requiring urgent CABG, 4 patients with acute myocardial infarction died but others were restored to NYHA class I to II. We conclude that it is important to aim at complete coronary revascularization in patients with poor left ventricular function and RC-CBCP achieves more effective myocardial protection during CABG in the patients.

Role of endogenous ANP in sodium excretion in rats with experimental pulmonary hypertension

To explore the roles of endogenous atrial natriuretic peptide (ANP) in the volume regulation, we examined effects of antiserum for ANP or a neutral endopeptidase inhibitor, thiorphan, in rats with monocrotaline (MCT)-induced pulmonary hypertension. ANP concentrations in the plasma and right ventricle and ANP mRNA in the right ventricle of MCT-treated rats were higher than in vehicle-treated rats. The administration of the ANP antiserum into the MCT-treated rats did not affect the right atrial pressure or blood pressure but significantly decreased urinary excretion of Na by 60%. No decrease occurred in the control rats. Thiorphan dose dependently increased the urinary excretion of Na by 140% without influencing the right atrial pressure or blood pressure. This natriuresis was associated with 50 and 450% increases in ANP concentrations in the plasma and urine, respectively. The degrees of increases in urinary Na excretion, ANP, and guanosine 3',5'-cyclic monophosphate were significantly greater in the MCT-treated rats than in the control rats. Thus an increased secretion of ANP in pulmonary hypertension actually contributes to Na excretion. The augmentation of endogenous ANP activity may further potentiate the compensatory role of this peptide in the regulation of body fluid volume.

Effects of the Fab fragment of digoxin antibody on the natriuresis and increase in blood pressure induced by intracerebroventricular infusion of hypertonic saline solution in rats

1. The effects of intravenous injection of Fab fragments of anti-digoxin IgG (Digibind) on the changes in blood pressure, urine volume and urinary sodium excretion after intracerebroventricular infusion of artificial cerebrospinal fluid with normal or high sodium concentration were examined in anaesthetized rats. 2. The biological efficacy of Digibind was confirmed by experiments in vitro and in vivo, which showed that pretreatment with Digibind completely abolished or significantly attenuated the aortic contractile response or pressor response to digoxin in guinea-pigs. 3. Infusion of high-sodium cerebrospinal fluid, but not normal-sodium cerebrospinal fluid, into the lateral brain ventricle of rats caused marked increases in blood pressure, urine volume and urinary sodium excretion. 4. Digibind did not significantly affect the increases in blood pressure, urine volume and urinary sodium excretion caused by intracerebroventricular infusion of high-sodium cerebrospinal fluid. 5. Digoxin-like immunoreactive factor may play a minor role, if any, in central nervous system-induced natriuresis in rats.

Acute acalculous cholecystitis complicating Mycoplasma pneumoniae infection

Mycoplasma pneumoniae infection has been associated with extrarespiratory manifestations. Gastrointestinal manifestations, gastroenteritis, hepatitis, and pancreatitis have also been reported.1,2 There have been no previous reports of acute cholecystitis complicating Mycoplasma pneumoniae infection. Acute acalculous cholecystitis is uncommon in childhood. We report on a child with acute cholecystitis during the course of Mycoplasma pneumoniae infection.