Activation of the adenosine triphosphate sensitive mitochondrial potassium channel is involved in the cardioprotective effect of isoflurane

The adenosine triphosphate-dependent potassium (K(ATP)) channel has been proposed to play an important role in the cardioprotective effect of isoflurane (ISO). However, the question of whether the K(ATP) channel, sarcolemmal or mitochondrial is the main contributor to the effect has not been clarified. The major aim of the present study was to determine whether or not the mitochondrial potassium channel was a site of action for ISO. Whether there was an acute "memory phase", in which drugs were not detected in the tissues, but the protective effect still remained in the ischemic preconditioning (IP) -like effect of ISO was also investigated. Dangling participle isolated rat hearts, a 20-min normothermic nonperfused phase was maintained to produce a global ischemia. Under these ischemic conditions, the effects of ISO, sodium 5-hydroxydecanoate (5HD: a selective mitochondrial K(ATP) channel antagonist), and ISO combined with 5HD on cardiac performance were examined. To all these four groups, (non-treated group, ISO group, 5HD group and ISO plus 5HD group, n=6 each) drugs were given for 30 min. After 10 min of drug-free perfusion (pre-ischemia restabilization period), 20 min of ischemia followed. Then the cardiac performance and the creatine kinase (CK) release during the reperfusion period were tested. In the non treated group and 5HD group, cardiac performance was stable during the treated period and pre-ischemia the restabilization period. In the ISO group and ISO plus 5HD group, heart rate (HR), left ventricular (LV) systolic pressure, and LV maximum rate of development of tension (dP/dtMax) during the drug-treated period became gradually and linearly worse. However, these values were the same as in the non-treated group and 5HD group at the end of the pre-ischemia restabilization period. So 5HD itself had no hemodynamic effect; nor did it have any influence on the actions of ISO. At the end of the pre-ischemia restabilization period, the significant hemodynamic differences among the groups diminished and ISO was not detected in the solution. In the post-reperfusion period, except for the ISO group, (non treated group, 5HD group and ISO plus 5HD group) cardiac performances were drastically decreased. ISO significantly ameliorated the dysfunction of cardiac output, LV systolic pressure and LV+dP/dtMax. The CK level in the coronary effluent during reperfusion was also significantly reduced by ISO. 5HD completely inhibited these cardiac effects of ISO. Activation of the adenosine triphosphate sensitive mitochondrial potassium channel is involved in the cardioprotective effect of ISO, and the action of this agent has an acute"memory phase" like ischemic preconditioning.

Nephrin is an important component of the barrier system in the testis

Nephrin, a gene product of the congenital nephrotic syndrome of the Finnish type (NPHS1), is a 1242-residue putative transmembrane protein of the immunoglobulin family of cell adhesion molecules. The expression of this gene is localized in rat and human glomerular epithelial cells. Here we report the expression of nephrin in various tissues other than the kidneys in mice. The expression of nephrin mRNA in various tissues of mice, including the kidneys, testes, spleen, thymus and brain, were first investigated by the RT-PCR method, and it was shown that a high level of nephrin mRNA could be detected in the testes of mice 1-6 weeks old. In situ hybridization revealed the expression of the nephrin gene in the Sertoli cells. Additionally, immunofluorescent staining studies indicated that nephrin was colocalized with anchoring protein ZO-1 in the mouse testis. From these results, it is inferred that nephrin is an important component of the barrier system in testes.

Microwave coagulation therapy with interruption of hepatic blood in- or outflow: an experimental study

PURPOSE

To determine how interruption of hepatic blood in- or outflow affects the coagulation diameter of microwave coagulation therapy (MCT) in the liver.

MATERIALS AND METHODS

Laparotomic MCT at 60 W for 1 minute was performed in 11 Landrace pigs. MCT was performed under six different conditions: without occlusion (Group N; in seven lobes of seven pigs); with occlusion of the hepatic artery (Group A; in five lobes of five pigs); with occlusion of the portal vein (Group P; in five lobes of five pigs); with occlusion of the hepatic artery and portal vein (Group AP; in six lobes of six pigs); with occlusion of the hepatic vein (Group V; in five lobes of four pigs); and with occlusion of the hepatic artery and vein (Group AV; in seven lobes of seven pigs). The maximum diameters for each group were compared.

RESULTS

The coagulation diameters (mean +/- SD) were 8.5 mm +/- 2.0, 10.0 mm +/- 1.6, 14.3 mm +/- 2.5, 14.4 mm +/- 2.4, 13.0 mm +/- 0.8, and 14.4 mm +/- 1.5 for Groups N, A, P, AP, V, and AV, respectively. The coagulation diameters for groups P, AP, V, and AV were statistically larger than those for groups N and A (P < .05). There was no significant difference between the coagulation diameters of Groups P, AP, V, and AV.

CONCLUSION

The coagulation diameter depends mainly on the portal venous flow. In addition of direct interruption of the portal vein, interruption of the hepatic vein can also result in a substantial increase in the coagulation diameter.

Anesthetic inhibition in ischemic and nonischemic murine heart: comparison with conscious echocardiographic approach

It is well known that the level of anesthesia obtained by intraperitoneal injection is variable and may alter cardiac function. In this study, we compared the effects of different anesthetics on cardiac function with the conscious state using high-resolution two-dimensional echocardiography in nonischemic and ischemic mice. Eighty-four mice were tested before and after surgery with ligation of the coronary artery. All 84 mice were studied in the conscious state and under high-dose intraperitoneal anesthesia. Twenty-two of 84 mice were studied under low-dose intraperitoneal anesthesia. Another 22 mice were also studied under gas anesthesia and spontaneous breathing. Experiments in the conscious state were performed by two investigators before the administration of anesthesia: one investigator held the animal and the transducer and the other operated the ultrasound equipment. Left ventricular systolic function was measured, and measurements obtained after surgery were compared with infarcted areas assessed by histological staining. Results showed that both high- and low-dose intraperitoneal anesthesia significantly reduced heart rates and left ventricular contractility in both pre- and postsurgical mice as opposed to conscious mice (P < 0.01). There were significantly higher correlation coefficients between mean fractional area change (FAC) and infarcted area in conscious state compared with high-dose intraperitoneal anesthesia (P < 0.05). The correlation coefficient between FAC and infarcted area during gas anesthesia was also significantly higher compared with high-dose intraperitoneal anesthesia (P < 0.05). In conclusion, conscious experiments or the use of gas anesthesia is preferred for echocardiographic assessment of cardiac function in mice because intraperitoneal injection significantly induces a significant reduction in heart rate and left ventricular systolic function.

Assessment of segmental wall motion abnormalities using contrast two-dimensional echocardiography in awake mice

Murine models of cardiac disease are becoming an important tool for studying pathophysiological processes. Development of methods to accurately assess ventricular function are therefore important. The purpose of this study was to evaluate the feasibility of echocardiographic assessment of segmental wall motion abnormalities in a murine model of myocardial infarction. Two-dimensional contrast (C+) and noncontrast (C-) echocardiography were performed in 76 awake mice 2 days before and 2 days after left coronary ligation. The short-axis images obtained with two-dimensional echocardiography and corresponding postmortem cross-sectional histological samples stained with Evans blue dye were each divided into 16 segments, and all matched segments were examined for correlation between wall motion abnormalities and myocardial hypoperfusion. With the use of contrast enhancement, the number of visualized segments was significantly increased (base: C- 86%, C+ 98%; midpapillary: C- 57%, C+ 89%; apex: C- 30%, C+ 74%). Agreement between echocardiographically assessed regional wall motion abnormalities and pathologically determined hypoperfusion in basal, midpapillary, and apical levels were 90%, 93%, and 93%, respectively. Agreement between echocardiographically normal wall motion and pathologically normal findings in basal, midpapillary, and apical levels were 99%, 88%, and 71%, respectively. Thus echocardiographic assessment of segmental wall motion in awake mice was feasible and the accuracy was improved with the use of a contrast agent.

New calculation of internal Ca(2+) recirculation fraction from alternans decay of postextrasystolic potentiation

In our previous studies, we calculated the internal Ca(2+) recirculation fraction (RF) after obtaining the beat decay constant (tau(e)) of the monoexponential component in the postextrasystolic potentiation (PESP) of the alternans decay by curve fitting. However, this method sometimes suffers from the sensitive variation of tau(e) with small noises in the measured contractilities of the 5th and 6th postextrasystolic (PES) beats in the tail of the exponential component. We now succeeded in preventing this problem by a new method to calculate RF without obtaining tau(e). The equation for the calculation in the new method expresses an alternans decay of PESP as a recurrence formula of PESP. It can calculate RF directly from the contractilities of the 1st through the 4th PES beats without any fitting procedure. To evaluate the reliability of the new method, we calculated RF from the alternans decay of PESP of the left ventricle (LV) of the canine excised cross-circulated heart preparation by both the original fitting and the new method. Although there was no significant difference in the mean value of the obtained RF between these two methods, the variance of RF was smaller with the new method than with the original method. Thus the new method proved useful and more reliable than the original fitting method.

Coupling interval from slow to tachycardiac pacing decides sustained alternans pattern

We discovered that the coupling beat interval from a slow to a tachycardiac pacing period considerably affected the pattern of the beat-to-beat alternation of the tachycardia-induced sustained contractile alternans. We analyzed the relationship between the coupling interval and the pattern and amplitude of the alternans in the isovolumic left ventricle of canine blood-perfused hearts. The alternans pattern and amplitude varied transiently over the first 30-50 beats and became gradually stable over the first minute in all 12 hearts. We discovered that stable alternans, even under the same tachycardiac pacing, had three different strong-weak beat patterns depending on the coupling interval. A relatively short coupling interval produced a representative sustained alternans of the strong and weak beats. A relatively long coupling interval produced a similar sustained alternans but in a reversed order of even- and odd-numbered beats counted from the coupling interval. However, sustained alternans disappeared after 1-3 specific coupling intervals. We conclude that ventricular pacing rate does not solely determine the pattern and amplitude of sustained contractile alternans induced by tachycardia.

Dietary curdlan increases proliferation of bifidobacteria in the cecum of rats

Significant increases in the amounts of short-chain fatty acids and lactate, and in numbers of bifidobacteria were observed in the cecum of curdlan (CD) -fed rats as compared with those of cellulose-fed ones. The in vitro proliferation of 5 species of bifidobacteria was markedly increased in the cultures containing the supernatant obtained from the cecal contents of CD-fed rats. These findings suggest that bifidus factors have been produced in the cecum of CD-fed rats.

Direct coronary artery perfusion from the left ventricle

OBJECTIVES

Trends in coronary bypass surgery require less invasive techniques and more conduits. We investigated the ability of direct coronary perfusion from the left ventricle to support regional and global cardiac function.

METHODS

A conduit was established between the left ventricle and left anterior descending coronary artery (n = 6) with an interposed Starling resistor that allowed for graded regulation of backward flow. Changes of coronary flow, regional function in the territory of the left anterior descending coronary artery, and reactive hyperemia were studied. In 3 separate dogs, functional tolerance to increased heart rate was tested. In another 3 dogs, left ventricle-left anterior descending and left ventricle-left circumflex coronary artery conduits were established simultaneously (double conduit), and global function was tested.

RESULTS

Without flow regulation, flow through the left ventricle-left anterior descending conduit exhibited high peaking (102 +/- 35 mL/min), midsystolic forward flow, and large pandiastolic backward flow (peaking at -47 +/- 22 mL/min). Mean coronary flow and regional function were maintained at 46.0% +/- 7.1% (35.8%-54.2%) and 45.3% +/- 29.1% (-1.8%-74.2%) of their respective normal values. When the Starling resistor was used to regulate backward flow, these values increased to 70.8% +/- 12.5% (56.8%-90.4%) and 70.2% +/- 27.8% (23.6%-107.7%), respectively. Coronary and functional reserve with a left ventricle-left anterior descending conduit were not observed. With the double conduit, global ventricular contractility indexed by end-systolic pressure-volume relation averaged 46% +/- 35% of its normal value.

CONCLUSIONS

A left ventricle-coronary artery conduit supplied approximately 45% of normal blood flow and regional function, and both were improved by regulation of backward flow. Therefore, a conduit from the left ventricle to an epicardial vessel could serve as a rapidly deployable means of revascularizing totally occluded coronary vessels for which suitable natural conduits are not available.

Evaluation of regional liver damage by magnetic resonance imaging with superparamagnetic iron oxide in rat liver

The purpose of this study was to investigate whether regional liver damage could be detected by means of enhanced MR imaging with a superparamagnetic iron oxide (SH U 555A) in an ischemia-reperfusion model of rat liver. Ischemic liver damage was induced in the right lobe by vascular clamping for 0 (sham), 30 (I-30), 60 (I-60), and 90 minutes (I-90). There was no significant difference in relative enhancement (RE) between the ischemic and nonischemic lobes in the sham, I-30 and I-60 groups, while RE of the ischemic lobe was significantly lower than that of its nonischemic counterpart in the I-90 group as seen on SH U 555A enhanced proton density spin echo images (P < 0.05). Histological examination revealed that iron deposits were significantly smaller in the ischemic than the nonischemic lobe in the I-90 group (P < 0.05), although there was no significant difference in the number of Kupffer cells. Our results indicate that severe regional liver damage can be evaluated by MR imaging with SH U 555A.

Total Ca2+ handling for E-C coupling in the whole heart: an integrative analysis

We assessed total Ca2+ handling (transport, flux) in excitation-contraction (E-C) coupling in a beating left ventricle (LV). We developed a new integrative analysis method that utilizes the internal Ca2+ recirculation fraction (RF), O2 consumption (V(O2)) for Ca2+ handling, and O2 cost of Emax (contractility index) of the LV. We obtained the RF from the beat constant of the exponential decay component of the postextrasystolic potentiation, and the O2 cost of Emax from V(O2) measured at different Emax. Our equation calculated the unknown total Ca2+ handling, futile Ca2+ cycling, and Ca2+ reactivity of Emax from the RF and Ca2+ handling V(O2). The calculated total Ca2+ handling fell between 30 and 110 micromol/kg, depending on Emax and pathological conditions. Our method also allowed an assessment of futile Ca2+ cycling and Ca2+ reactivity of Emax in a beating LV. These data are not available using conventional methods. Our method can be used to better understand the pathophysiology of total Ca2+ handling in a beating heart.

Novel acyl-CoA synthetase in adrenoleukodystrophy target tissues

X-linked adrenoleukodystrophy (X-ALD) is a neurodegenerative disorder characterized by demyelination of white matter. The X-ALD gene product adrenoleukodystrophy protein (ALDP) is expressed broadly among various tissues. However, deficiency of functional ALDP exclusively impairs brain, adrenal gland, and testis. Thus, loss of ALDP function is assumed to involve inactivation of a putative mediating factor that functions in a tissue-specific manner. Here we cloned a mouse cDNA encoding a novel protein, Lipidosin, that possesses long-chain acyl-CoA synthetase (LCAS) activity. Lipidosin is expressed exclusively in mouse brain, adrenal gland, and testis, which are affected by X-ALD. LCAS activity of Lipidosin was diminished by mutation of conserved amino acids within the AMP-binding domain. Mutation of the Drosophila homologue of Lipidosin has been reported to cause neuronal degeneration. Thus, Lipidosin may mediate the link between ALDP dysfunction and the impairment of fatty acid metabolism in X-ALD.

Rapidly progressive polymyositis with elevated antiacetylcholine receptor antibody activity

We report a 51-year-old woman with polymyositis accompanied by a high titer of antiacetylcholine receptor antibody. The patient presented with weakness of grip strength followed by rapidly progressive dyspnea, which required mechanical ventilation. She was treated with a glucocorticoid and came off the respirator one week later. Antiacetylcholine receptor antibody activity was elevated in the acute phase and decreased during recovery, although other signs of myasthenia gravis were negative. This patient suggested that in cases of rapidly progressive bulbar palsy and limb muscle weakness, it is necessary to include polymyositis associated with elevated antiacetylcholine receptor antibody activity in the differential diagnosis.

Radio frequency transmyocardial revascularization enhances angiogenesis and causes myocardial denervation in canine model

BACKGROUND AND OBJECTIVE

Transmyocardial revascularization (TMR) relieves angina and improves exercise tolerance in patients. Angiogenesis and myocardial denervation have been proposed as factors contributing to these benefits. To test whether radio frequency transmyocardial revascularization (RF-TMR) enhances angiogenesis and causes myocardial denervation.

STUDY DESIGN/MATERIALS AND METHODS

RF-TMR channels were created in 12 dogs which survived up to 4 weeks. Bromodeoxyuridine was administered subcutaneously to mark proliferating cells as an assay of angiogenesis. Western blot analysis of tyrosine hydroxylase and blood pressure response to topical bradykinin were used as indices of myocardial denervation.

RESULTS

RF-TMR increased local vascularity by an average of 50%, whereas the rate of vascular cell proliferation was tripled over that of the untreated region. Changes in mean arterial pressure with bradykinin and tyrosine hydroxylase content were significantly decreased in RF-TMR regions as compared with normal myocardium in the same hearts.

CONCLUSION

RF-TMR enhances angiogenesis and causes myocardial denervation in canine myocardium as with laser TMR.

Defect in cell wall integrity of the yeast saccharomyces cerevisiae caused by a mutation of the GDP-mannose pyrophosphorylase gene VIG9

The Saccharomyces cerevisiae VIG9 gene encodes GDP-mannose pyrophosphorylase, which synthesizes GDP-mannose from GTP and mannose-1-phosphate. Although the null mutant was lethal, the vig9 mutants so far obtained showed no growth defect but immature protein glycosylation and drug hypersensitivity. During our search for cell-wall mutants, we found a novel temperature-sensitive mutant, JS30, which required an osmotic stabilizer for viability. JS30 excreted cell surface proteins in the medium without any indication of cell lysis. Although conventional genetic analysis using mating was impossible, by detailed characterization of JS30 including an in vitro enzyme assay and nucleotide sequencing, we found the defect of JS30 was due to a mutation in the VIG9 gene. These results indicated a critical role of GDP-mannose in maintenance of cell-wall integrity.

Role of the liver in alloimmune response following inoculation of donor spleen cells

The liver is thought to be an immunologically privileged organ in the response to inoculated antigens. We previously demonstrated that it is possible to localize inoculated antigens to the liver alone or only to extrahepatic tissue using orthotopic syngeneic liver transplantation (OSLT). In this study, we analyzed more detailed mechanisms of the anti-alloimmune response in the liver. DA rat spleen cells were systemically injected into WS rats (donor spleen cell inoculation, DSI). In the sensitized liver-grafted (SLG) group, after DSI, liver grafts were retrieved from sensitized WS rats, then transplanted into naive WS rats. In the sensitized liver-removed (SLR) group, after DSI, WS rats were totally hepatectomized and given livers transplanted from naive WS rats. All the rats were challenged with heterotopic heart grafts 10 days after DSI. Mean heart graft survival in the control, DSI, SLG, and SLR groups were 11.6+/-1.6, 10.7+/-2.4, 4.4+/-1.0, and 24.6+/-6.3 days, respectively. Accelerated rejection in the SLG group as well as graft prolongation in the SLR group disappeared when OSLT was performed 2 days after DSI or later. Irradiation of DA splenocytes before inoculation did not alter graft survival in SLG. However, pretreatment with gadolinium chloride prior to DSI attenuated the antidonor response in the SLG group. In conclusion, a vigorous antidonor response occurred in the liver after systemic inoculation of spleen cells. It peaked I day after DSI and disappeared rapidly. Kupffer cells seemed to play an important role in this phenomenon.

Dietary n-3 polyunsaturated fatty acid and status of immunocompetent cells involved in innate immunity in female rats

The aim of this study was to estimate the contributions of dietary n-3 polyunsaturated fatty acid (PUFA), a representative dietary immunosuppressant, to the activity of both alveolar macrophages (AM) and natural killer (NK) cells, and compare them to those of n-6 PUFA. Twelve 5-week-old female Sprague-Dawley rats were divided into two dietary groups, one fed a 10% fat diet for 9 weeks enriched with n-3 PUFA (n-3 diet) and the other an n-6 PUFA (n-6 diet). AM reduced the release of nitric oxide, monocyte chemoattractant protein 1 and tumor necrosis factor alpha in the rats fed the n-3 diet, compared with rats fed the n-6 diet. NK cell activity was reduced by consumption of the n-3 diet. This study suggests that consumption of n-3 PUFA can ameliorate pulmonary inflammatory disorders which are affected by the reduction of not only proinflammatory cytokines but also chemokine released from AM.

Naturally anergic and suppressive CD25(+)CD4(+) T cells as a functionally and phenotypically distinct immunoregulatory T cell subpopulation

A CD4(+) T cell subpopulation defined by the expression levels of a particular cell surface molecule (e.g. CD5, CD45RB, CD25, CD62L or CD38) bears an autoimmune-preventive activity in various animal models. Here we show that the expression of CD25 is highly specific, when compared with other molecules, in delineating the autoimmune-preventive immunoregulatory CD4(+) T cell population. Furthermore, although CD25 is an activation marker for T cells, the following findings indicate that immunoregulatory CD25(+)CD4(+) T cells are functionally distinct from activated or anergy-induced T cells derived from CD25(-)CD4(+) T cells. First, the former are autoimmune-preventive in vivo, naturally unresponsive (anergic) to TCR stimulation in vitro and, upon TCR stimulation, able to suppress the activation/proliferation of other T cells, whereas the latter scarcely exhibit the in vivo autoimmune-preventive activity or the in vitro suppressive activity. Second, such activated or anergy-induced CD25(-) spleen cells produce various autoimmune diseases when transferred to syngeneic athymic nude mice, whereas similarly treated normal spleen cells, which include CD25(+)CD4(+) T cells, do not. Third, upon polyclonal T cell stimulation, CD25(+)CD4(+) T cells express CD25 at higher levels and more persistently than CD25(-)CD4(+) T cell-derived activated T cells; moreover, when the stimulation is ceased, the former revert to the original levels of CD25 expression, whereas the latter lose the expression. These results collectively indicate that naturally anergic and suppressive CD25(+)CD4(+) T cells present in normal naive mice are functionally and phenotypically stable, distinct from other T cells, and play a key role in maintaining immunologic self-tolerance.

[A case of unilateral recurrent calf myalgia with muscle edema due to venous congestion]

We report a 38-year-old man who had three episodes of pain and swelling in the right calf from the age of 27 years. On each episode, pain worsened gradually, lasted for a few months and subsided spontaneously. Venography performed at the first episode was reported to be unremarkable. At the third episode, physical examinations showed tender and hard muscles in the right calf without findings of knee arthritis. The right calf pain became stronger when standing than when lying and on the ankle dorsiflexion. Laboratory examinations showed leukocytosis, a slightly elevated level of CRP, and normal CK levels. MRI showed diffuse high intensities in the right soleus and the lateral head of right gastrocnemius on T2-weighted images, where CT showed slightly low densities. To rule out focal myositis, the right soleus was biopsied. The muscle specimen showed perimysial and endomysial edema, dilatation of venules and capillaries, and focal mononuclear cell infiltration in the venule wall. Intermyofibrillar networks were well preserved. There were no necrotic or regenerating fibers, nor sarcolemmal expression of HLA-ABC. On electron microscopy, the processes of fibroblasts in the endomysium were swollen. This case illustrated muscle edema caused by local venous congestion possibly due to venulitis of unknown cause.