Synchrotron microangiography reveals configurational changes and to-and-fro flow in intramyocardial vessels

In 8 dogs, in situ microangiography using synchrotron radiation visualized penetrating transmural arteries (PTAs) with a diameter of >60 micrometers and allowed quantitation of vessel diameters of >140 micrometers. Myocardial contraction reduced the vascular short-axial diameters to 87 +/- 17% (n = 62, P < 0.001, paired t-test) of the end-diastolic values and increased the longitudinal dimension to 129 +/- 5% (n = 45, P < 0.001). The diameter reduction in the subendocardial PTA segments was significantly more marked than that in the subepicardial PTA segments (60 +/- 12 vs. 88 +/- 12%, n=13, P < 0.001, paired t-test). Intracoronary administration of dobutamine (0.1 micrograms. kg-1. min-1) increased, and in contrast, partial clamping of the coronary artery (ischemia) decreased, the configurational changes. To-and-fro blood flow was clearly observed in PTAs with visual identification of capacitive backflow, resistive forward flow during ischemia on coronary arteriography, and even under baseline conditions in coronary venography. Thus this method advances our understanding of mechanical influences on the coronary circulation.

Benidipine, a long-acting Ca channel blocker, limits infarct size via bradykinin- and NO-dependent mechanisms in canine hearts

Amlodipine increases NO levels in coronary vessels and aorta via bradykinin-dependent mechanisms in vitro. We have previously reported that a long-acting Ca channel blocker, benidipine, increases cardiac NO levels in ischemic canine hearts, suggesting that benidipine may also protect against ischemia and reperfusion injury via bradykinin- and NO-dependent mechanisms. We examined this possibility. In open chest dogs, the left anterior descending coronary artery was perfused with blood through a bypass tube and was occluded for 90 min followed by 6 hours of reperfusion. Infarct size was assessed by TTC staining at 6 hours of reperfusion. When benidipine doses of 50, 100, and 200 ng/kg/min were infused via the bypass tube between 10 min prior to the onset of ischemia and after 60 min of reperfusion, systemic blood pressure did not change significantly. Infarct size decreased with the administration of benidipine (50, 100, and 200 ng/kg/min) when compared to the untreated condition (24.8+/-2.5, 17.3+/-3.1, and 16.5+/-2.0 vs. 43.4+/-5.6%, respectively) associated with the increased release of NO and bradykinin in the coronary venous blood upon reperfusion. Myeloperoxidase activity of the myocardium increased after 6 hours of reperfusion, which was attenuated by benidipine. The limitation of infarct size and the increase in myeloperoxidase activity were completely blunted by either L-NAME or HOE140. There were no significant differences in collateral blood flow assessed by the microsphere method after 45 min of ischemia for any of the groups. Thus, we conclude that the Ca channel blocker, benidipine, limits infarct size via bradykinin- and NO-dependent mechanisms.

New nonradioactive microspheres and more sensitive X-ray fluorescence to measure regional blood flow

We developed new nonradioactive microspheres and used more sensitive X-ray fluorescence spectrometers than used previously to measure regional blood flow in the heart and other organs. We demonstrated the chemical stability of eight kinds of heavy element-loaded microspheres and validated their use for regional blood flow measurement by comparing duplicate flows measured with radioactive and/or nonradioactive microspheres in both acute and chronic dog experiments. The wavelength-dispersive spectrometer (Philips PW 1480) has a higher sensitivity than the previously described X-ray fluorescent system and reduced the number of microspheres required for accurate measurement. The fine energy resolution of this system makes it possible to increase the numbers of different kinds of microspheres to be quantitated, but at present only eight kinds are available. We also used a synchrotron radiation-excited energy dispersive spectrometer. The monochromatic synchrotron radiation allowed us to obtain much higher signal-to-background ratios of X-ray fluorescence spectra than with the wavelength-dispersive system (50 dB more for Zr-loaded microspheres) and will enable analysis of fluorescent activity in smaller regions (< 20 mg) than the radioactive method does.

Gonadotropin-releasing hormone increases serum human chorionic gonadotropin in pregnant women

Hypothalamic decapeptide, gonadotropin-releasing hormone (GnRH) has been found to stimulate human chronic gonadotropin (hCG) secretion by trophoblast cells in vitro. To determine the biological effect of GnRH on the release of hCG in vivo, we studied the effect of the administration of GnRH on the serum levels of human chronic gonadotropin (hCG) during pregnancy. Serum hCG levels were measured before and 15, 30, and 60 min after the intravenous administration of 100 micrograms of GnRH to 22 volunteers with normal pregnancy. Nine of the 12 (75%) women responded to GnRH in the first trimester, while only 1 of the 5 women (20%) responded to GnRH in the second trimester. None of the 5 women tested in the third trimester showed a significant response of hCG to the injection of GnRH. The average increase in hCG during the first, second and third trimester was 160.7 +/- 13.5%, 111.0 +/- 7.4% and 95.0 +/- 2.3%, respectively (mean +/- SEM). Whereas the pregnant courses of all the cases were uneventful and normal, other abnormal pregnancies were also investigated with informed consents. Three patients with missed abortions also showed a significant response of hCG to GnRH (increase: 136.7 +/- 8.5%) when GnRH was administered before curettage of the uterine cavity. However, 4 patients with unruptured ectopic pregnancies did not respond to GnRH stimulation. These findings indicate that GnRH can stimulate the release of hCG by the placenta in vivo, consistent with the previous in vitro study, while the responsiveness depend on gestational age and the implantation site.

Branching patterns of intramural coronary vessels determined by microangiography using synchrotron radiation

The intramural coronary artery (IMCA) with a diameter of 50-500 micrometers is critical for blood supply to the inner layers of heart muscle. We introduced digital measurement to microangiography using monochromatic synchrotron radiation and quantified branching patterns of the IMCA, the epicardial coronary artery (EPCA), and the distal ileal artery (DIA). The pre- and postbranching diameters were measured (95-1,275 micrometers) in seven dogs. A typical arterial segment divided into two nearly equivalent branches, and a regression line of daughter-to-mother diameter plots was almost identical among the EPCA (y = 0.838x - 16.7 in micrometers), IMCA (y = 0.737x - 2.18), and DIA (y = 0.755x + 8.63). However, a considerable difference was present at a segment where a proximal IMCA branched off from an EPCA (y = 0.182x + 90.2). Moreover, a proximal IMCA diameter had no relationship to the branching order from an EPCA. The precision of this method was confirmed by the good correlation of diameter measurements between two independent observers (r = 0.999, y = 1.02x - 1.07). In conclusion, using digital microangiography we demonstrated that the self-similar branching pattern of coronary arteries was discrete at the connection between the IMCA and EPCA.

Nifedipine limits infarct size via NO-dependent mechanisms in dogs

OBJECTIVES

Amlodipine increases NO levels in coronary vessels and aorta via bradykinin-dependent mechanisms in vitro. We have previously reported that nifedipine increases cardiac NO levels in the ischemic canine hearts, suggesting that nifedipine may also have protective effects against ischemia and reperfusion injury, because the enhancement of NO production limits infarct size. We tested whether nifedipine limits infarct size via NO-dependent mechanisms.

METHODS

In open chest dogs, the left anterior descending coronary artery was perfused with blood through a bypass tube and occluded for 90 min followed by 6 hours of reperfusion. Infarct size was assessed at 6 hours of reperfusion. Nifedipine of 3 or 6 microg/kg/min was infused into the bypass tube between 10 min prior to the onset of ischemia and 60 min of reperfusion.

RESULTS

Neither systemic blood pressure nor heart rate changed during infusion of nifedipine. Infarct size was reduced by the administration of nifedipine (3 or 6 microg/kg/min) compared with the untreated condition (25.6+/-2.6 and 19.1+/-3.5 vs. 43.4+/-5.6%, respectively), which was completely blunted by L-NAME (45.0+/-3.6 and 45.4+/-4.2 vs. 47.9+/-3.9% in the nifedipine (3 or 6 microg/kg/min) with L-NAME groups vs. the L-NAME group). Myeloperoxidase activity of the myocardium increased after 6 hours of reperfusion, which was attenuated by nifedipine. The limitation of infarct size and the attenuation in myeloperoxidase actiivity were completely blunted by L-NAME. There were no significant differences in collateral blood flow at 45 min of ischemia between each group.

CONCLUSIONS

We conclude that the Ca channel blocker, nifedipine, limits infarct size via NO-dependent mechanisms.

Impaired tumor phenotypes in class II major histocompatibility complex antigen-inducible cells originated from human lung adenocarcinoma

The class II major histocompatibility complex (MHC) antigens play important roles in T cell activation and are thought to be involved in tumor development. Using anti-class II antibodies with interferon gamma (IFN-gamma), we have here selected class II MHC antigen positive cancer cells from the human lung adenocarcinoma cell line A549, which is originally negative (> 95%) for the antigens. A part of the class II antigen-positive cells presented a flat morphology, which was not observed in the parental A549 cells. Class II antigen expression in these flat cells was IFN-gamma inducible; there was a correlation between the inducibility and phenotypic changes. A class II antigen-inducible flat subline restored the ability of contact inhibition and anchorage-dependent growth as well as lost tumorigenicity in athymic mice.

Role of activation of ectosolic 5'-nucleotidase in the cardioprotection mediated by opening of K+c channels

We tested the hypothesis that the opening of ATP-sensitive K+ channels contributes to activation of ectosolic 5'-nucleotidase and the infarct size-limiting effect of ischemic preconditioning. In open-chest dogs, the left anterior descending coronary artery was occluded four times for 5 min each, separated by a 5-min period of reperfusion (ischemic preconditioning, n = 8). After this procedure, the coronary artery was occluded for 90 min, followed by 6 h of reperfusion. Infarct size was smaller in this group than in the group (control, n = 8) with a 45 min interval instead of the ischemic preconditioning procedure (40.1 +/- 3.9 vs. 6.4 +/- 1.9%). Glibenclamide blunted the infarct size-limiting effect of ischemic preconditioning (infarct size, 37.3 +/- 5.8%; n = 7), and transient exposures to cromakalim and nicorandil mimicked it [infarct size, 10.1 +/- 3.1 (n = 7) and 11.1 +/- 2.7% (n = 8), respectively]. Ectosolic and cytosolic 5'-nucleotidase activity increased in the ischemic preconditioning group compared with that in the control group; this preconditioning-induced increase in 5'-nucleotidase activity was blunted by glibenclamide (n = 5) and mimicked by cromakalim (n = 5) and nicorandil (n = 5). The infarct size-limiting effect due to cromakalim and nicorandil was blunted by alpha,beta-methyleneadenosine 5'-diphosphate, an inhibitor of ectosolic 5'-nucleotidase [infarct size, 37.7 +/- 5.6 (n = 9) and 36.8 +/- 4.8% (n = 7), respectively] and 8-sulfophenyltheophylline (infarct size with cromakalim, 44.7 +/- 4.6%; n = 7). We conclude that activation of ectosolic 5'-nucleotidase due to the openers of ATP-sensitive K+ channels contributes to the infarct size- limiting effect of ischemic preconditioning.

Bidirectional effects of aminophylline on myocardial ischemia

BACKGROUND

Aminophylline blocks adenosine receptors and increases levels of plasma catecholamines. We investigated the effect of aminophylline on myocardial ischemia by varying its severity and attempted to identify the mechanism by which aminophylline modulates myocardial ischemia in the canine model.

METHODS AND RESULTS

In 41 open-chest dogs, the left anterior descending coronary artery was cannulated and perfused with blood through a bypass tube from the left carotid artery. When coronary blood flow (CBF) was reduced to 80% of the control, aminophylline increased fractional shortening (FS) from 11.0 +/- 0.4% to 18.5 +/- 1.7% (P < .05) and lactate extraction ratio (LER) from 7.5 +/- 0.1% to 13.6 +/- 1.0% (P < .01). The endocardial to epicardial flow ratio (Endo/Epi ratio) of regional myocardium was also increased. Release of adenosine was increased compared with the nonischemic condition (7 +/- 3 versus 28 +/- 5 pmol/mL). Prazosin, an alpha 1-adrenoceptor antagonist, blunted the aminophylline-induced improvement in contractile and metabolic function. Administration of 8-phenyltheophylline, a selective antagonist of adenosine receptors, did not increase FS, LER, or the Endo/Epi ratio when CBF was reduced to 80% of control. When CBF was reduced to 60% of control, aminophylline did not change the metabolic and contractile function. In contrast, when CBF was reduced to 33% of control, release of adenosine was increased markedly (243 +/- 19 pmol/mL) and aminophylline induced decreases in FS, LER, and Endo/Epi ratio similar to those observed with 8-phenyltheophylline.

CONCLUSIONS

Aminophylline had opposite effects on the ischemic myocardium depending on the severity of ischemia. It improved mild ischemia but worsened severe ischemia. The beneficial effect of aminophylline was attributable to alpha 1-adrenoceptor stimulation, which improves endomyocardial flow in the ischemic myocardium. The deleterious effect was attributable to the aminophylline-induced blockade of adenosine receptors.

Screening of novel nuclear receptor agonists by a convenient reporter gene assay system using green fluorescent protein derivatives

Nuclear receptors represent a very good family of protein targets for the prevention and treatment of diverse diseases. In this study, we screened natural compounds and their derivatives, and discovered ligands for the retinoic acid receptors (RARs) and the farnesoid X receptor (FXR). In the reporter assay systems of nuclear receptors presented here, two fluorescent proteins, enhanced yellow fluorescent protein (EYFP) and enhanced cyan fluorescent protein (ECFP), were used for detection of a ligand-based induction and as an internal control, respectively. By optimizing the conditions (e.g., of hormone response elements and promoter genes for reporter plasmids), we established a battery of assay systems for ligands of RARs, retinoid X receptor (RXR) and FXR. The screening using the reporter assay system can be carried out without the addition of co-factors or substrates. As a result of screening of more than 140 compounds, several compounds were detected which activate RARs and/or FXR. Caffeic acid phenylethyl ester (CAPE), known as a component of propolis from honeybee hives, and other derivatives of caffeic acid up-regulated the expression of reporter gene for RARs. Grifolin and ginkgolic acids, which are non-steroidal skeleton compounds purified from mushroom or ginkgo leaves, up-regulated the expression of the reporter gene for FXR.

Vesnarinone limits infarct size via adenosine-dependent mechanisms in the canine heart

BACKGROUND

Recently, vesnarinone, a synthetic inotropic agent, was reported to inhibit adenosine transport into cells, which may increase adenosine levels in the heart and in turn mediate cardioprotection. Thus, vesnarinone may also have protective effects in sustained ischemia-reperfusion, because adenosine limits infarct size.

METHODS AND RESULTS

In open-chest dogs, the left anterior descending coronary arteries were occluded for 90 minutes followed by 6 hours of reperfusion. Vesnarinone limited infarct size compared with controls (6.8+/-2.2% versus 44.7+/-3.9%), which was completely reversed by a nonselective adenosine receptor antagonist, 8-sulfophenyltheophylline (44.1+/-6.8%), and partially blunted by an inhibitor of ecto-5'-nucleotidase, alpha,beta-methyleneadenosine 5'-diphosphate (AMP-CP, 28.9+/-4.7%). Dipyridamole, an inhibitor of adenosine uptake into cells, only modestly limited infarct size (27.4+/-5.5%). Furthermore, vesnarinone increased adenosine release during coronary hypoperfusion, which was attenuated by AMP-CP. In vitro, vesnarinone increased the activity of ecto-5'-nucleotidase of the myocardium.

CONCLUSIONS

We conclude that vesnarinone potently limits infarct size via adenosine-dependent mechanisms, mainly through activation of ecto-5'-nucleotidase.

Control of higher-order structures of zinc chlorophyll coordination polymers

The higher-order structures of the zinc chlorophyll coordination polymers were controlled by the regiochemistry of the coordination sites.

Protein tyrosine kinase is not involved in the infarct size-limiting effect of ischemic preconditioning in canine hearts

Protein kinase C (PKC) plays an important role in ischemic preconditioning (IP). Because (1) tyrosine kinase is located at the downstream of PKC for IP in the rabbit hearts and (2) we have reported that ecto-5'-nucleotidase is the substrate for PKC and plays a crucial role for the infarct size-limiting effect, we tested whether tyrosine kinase activation contributes to either activation of ecto-5'-nucleotidase or the infarct size-limiting effect of the early phase of IP in the canine heart. In dogs, the IP procedure (4 cycles of 5-minute occlusion of coronary artery) and exposure to 12, 13-phorbol myristate acetate (PMA) each activated myocardial ecto-5'-nucleotidase and Lck tyrosine kinase. Genistein (10, 30, and 100 microg. kg(-)(1). min(-)(1) IC), an inhibitor of tyrosine kinase, attenuated the activation of Lck tyrosine kinase but did not attenuate the activation of ecto-5'-nucleotidase due to either IP or PMA. In the other canine hearts, IP attenuated infarct size (49+/-5 versus 11+/-3 or 16+/-3%, P<0.01) due to 90 minutes of coronary occlusion followed by 6 hours of reperfusion, which was not blunted by 3 or 2 (30 and 100 microg. kg(-)(1). min(-)(1)) doses of genistein (infarct sizes, 15+/-4, 13+/-4, and 13+/-3%, respectively, and 17+/-3 and 15+/-4%, respectively) or lavendustin A. Tyrosine kinase does not activate ecto-5'-nucleotidase or trigger the infarct size-limiting effect of the early phase of IP in canine hearts.

Modulation of adrenergic coronary vasoconstriction via ATP-sensitive potassium channel

We examined humoral and/or locally produced vasoactive factors involved in modulating sympathetic coronary vasoconstriction via the ATP-sensitive K (KATP) channel in 42 anesthetized dogs. Glibenclamide (30 micrograms.kg-1.min-1 ic or 0.6 mg.kg-1.min-1 left atrial injection) augmented coronary vascular resistance (CVR) at baseline and during cardiac sympathetic nerve stimulation (2-20 Hz), with a greater increase seen in the subepicardial region than in the subendocardial region both during beta-adrenergic receptor blockade and alpha- and beta-receptor blockade [P < 0.05 and P < 0.05 (n = 6 and 18 dogs), analysis of variance]. In contrast, pinacidil (10 micrograms.kg-1.min-1; n = 8 dogs) suppressed CVR. Glibenclamide enhanced CVR response to locally administered norepinephrine of 0.001-0.1 microgram.kg-1.min-1 (P < 0.05, analysis of covariance; n = 5 dogs) but did not enhance norepinephrine or neuropeptide Y overflow (n = 18 dogs). CVR was not modified by calcitonin gene-related peptide (CGRP) antagonist [CGRP-(8-37)], 8-phenyltheophylline, or N omega-nitro-L-arginine (n = 11 dogs). Thus sympathetic coronary vasoconstriction is modified by coronary vascular KATP channels with a transmural difference. However, CGRP, adenosine, and endothelial nitric oxide production are not involved in the modulation.

Dantaxusins A and B, two new taxoids from Taxus yunnanensis

Two new taxane diterpenes, dantaxusin A [5 alpha-cinnamoyloxy-2 alpha,7 beta,13 alpha-triacetoxy-2(3-->20)abeo-taxa-4(20),11-diene-9,10-dione (1)] and dantaxusin B [5 alpha-cinnamoyloxy-9 alpha-hydroxy-10 beta,13 alpha-diacetoxytaxa-4(20),11-diene (2)], were isolated from an ethanol extract of the aerial parts of Taxus yunnanensis along with taxuspine B, 2-deacetoxytaxinine J, taxuyunnanine C, taxinine B, taxuspine C, and taxinine NN-4. The structures of 1 and 2 were established on the basis of 1D and 2D NMR and HRMS spectroscopic methods.

Effects of exposure to sulfuric acid-aerosol on airway responsiveness in guinea pigs: concentration and time dependency

We investigated the concentration and time dependency of the effects of exposure to sulfuric acid (H2SO4) aerosol on airway responsiveness. Two hundred and sixteen male Hartley guinea pigs were used. The animals were divided into 3 groups (n = 72/group), with 1 group being exposed to filtered air and the other 2 to 1.0 mg/m3 or 3.2 mg/m3 H2SO4 aerosol. In each group, the animals were divided into 4 subgroups (n = 18/subgroup), with exposure terms of 3 d (24 h/d), 7 d, 14 d, and 30 d. Specific airway resistance (SRaw) under room air (SRaw0) and airway responsiveness were determined 1 wk before the beginning of exposure and on the day of termination of the exposure. Specific airway resistance values under room air (SRaw0) prior to and after exposure were compared. There was no significant change in SRaw0 after the exposure to filtered air, 1.0 mg/m3, or 3.2 mg/m3 H2SO4 aerosol. Our results also showed that exposure to filtered air or 1 mg/m3 H2SO4 aerosol did not cause any significant change in airway responsiveness to inhaled histamine aerosol, expressed as the effective concentration of histamine (EC200His) that produced a doubling of SRawNaCl (SRaw after exposure to aerosol of 0.9% NaCl saline). On the contrary, exposure to 3.2 mg/m3 H2SO4 aerosol induced transient airway hyporesponsiveness after a 3-d exposure [EC200His prior to and after exposure: 1.35 +/- 0.28 and 2.23 +/- 0.22 mM (p < .01), respectively] and then transient hyperresponsiveness after a 14-d exposure [EC200His prior to and after exposure: 1.65 +/- 0.21 and 0.95 +/- 0.23 mM (p < .01), respectively]. Overall, the present results revealed that (1) 1.0 mg/m3 or 3.2 mg/m3 H2SO4 aerosol had no significant effect on SRaw0 during a 30-d exposure period, (2) a high concentration (3.2 mg/m3) of H2SO4 aerosol affected airway responsiveness during the 30-d exposure, while a low concentration (1.0 mg/m3) of H2SO4 aerosol did not, and (3) the effect of exposure to 3.2 mg/m3 H2SO4 aerosol on airway responsiveness was transient and stimulatory or inhibitory, depending on the duration of exposure.

Ectoparasites of the Pallas squirrel, Callosciurus erythraeus, introduced to Japan

The squirrel Callosciurus erythraeus (Pallas) (Rodentia: Sciuridae) was intentionally introduced to Japan in 1935 and has become established throughout much of the country. Although they live mainly in forests, Pallas squirrels come into gardens and are frequently fed by people or kept as pets, so their ectoparasites could be of potential medical as well as veterinary importance. During 2001-2003 we conducted the first ectoparasite survey of Pallas squirrels in Japan. From 105 C. erythraeus captured in Kamakura District of Kanagawa Prefecture on Honshu Island, three types of ectoparasite were found: 52 specimens of the sucking louse Neohaematopinus callosciuri Johnson (Anoplura: Haematopinidae), 26 fleas Ceratophyllus (Monopsyllus) anisus Rothschild (Siphonaptera: Ceratophyllidae) and four nymphs of the tick Haemaphysalis flava Neumann (Acari: Ixodidae) on 22, 13 and one squirrels, respectively. Evidently in Japan C. erythraeus carries relatively few ectoparasite species; this may be a contributory factor to their invasive success. Further investigations are needed to assess risks of zoonotic transmission of plague or murine typhus by C. anisus, of louse-borne typhus by N. callosciuri and of tularaemia and especially Japanese spotted fever (Rickettsia japonica) by H. flava.

Inhibition of matrix metalloproteinase-2 activity by siderophores of Pseudomonas species

To obtain a novel matrix metalloproteinase (MMP) inhibitor produced by bacteria, we have focused on the chelating activity of siderophores. Several siderophore-producing bacteria were isolated from soil using chrome azurol S agar plates and then the effect of siderophores on MMP-2 activity was assayed by gelatin zymography. The results showed that partially purified siderophores from ten isolated strains inhibited MMP-2 activity. Among these strains, two were non-fluorescent and eight were fluorescent Pseudomonas species. From these eight strains, pyoverdine-type siderophores were detected. The Zn(2+)-chelating activity of these siderophores correlated with the inhibition of MMP-2 activity. Therefore, it is considered that siderophores such as pyoverdines inhibit MMP-2 activity by chelating Zn(2+) on the active site of MMP-2.

Is superoxide demonstration by electron-spin resonance spectroscopy really superoxide?

A recent study has indicated that the generation of an oxygen radical in freeze-clamped myocardium on reperfusion can be directly demonstrated using electron-spin resonance spectroscopy (ESR). However, the results need to be analyzed with caution, since artifactual radicals are misleading problems common to this method. To test whether that reported superoxide is truly the biologically existing radical or an artifactual radical, we performed experiments using isolated, perfused rat and rabbit hearts and open-chest canine hearts subjected to ischemia/reperfusion. Radicals were freeze trapped at 77 degrees K, and ESR measurements were made. The ESR spectra exhibited four free radicals. Among these, two radicals which had been previously claimed as superoxide and a nitrogen-centered radical were shown as mechanically yielded artifactual radicals. These were produced by pulverization of the frozen sample. In artifact-free samples, superoxide could not be detected. The radicals native to the myocardium were identified as coenzyme Q10-. and another radical the species of which remains unclear.

Improvement by 5-amino-4-imidazole carboxamide riboside of the contractile dysfunction that follows brief periods of ischemia through increases in ecto-5-nucleotidase activity and adenosine release in canine hearts

5-Amino-4-imidazole carboxamide (AICA) riboside increases adenosine release in ischemic myocardium, suggesting that AICA riboside improves contractile dysfunction. In 49 open-chest dogs, contractile function assessed by fractional shortening (FS) was observed 3 h after the onset of reperfusion following 15 min of occlusion of the left anterior descending coronary artery. During reperfusion, the treatment with AICA riboside increased adenosine concentration in the coronary venous blood (536+/-44 vs. 281+/-21 pmol/ml at 3 min of reperfusion, p<0.001) and peak coronary hyperemic flow (367+/-13 vs. 300+/-21 ml/100 g per min, p<0.001) when compared with the untreated group. FS at 3h of reperfusion increased in the AICA riboside group (21.1+/-2.3 vs. 12.8+/-0.6% in the untreated group, p<0.001). AICA riboside increased myocardial ecto-5'-nucleotidase activity. Administration of adenosine also augmented coronary hyperemic flow and increased FS to the levels of the AICA riboside group. Either 8-phenyltheophylline (an antagonist of adenosine receptors) or alpha,beta-methylene-adenosine 5'-diphosphate (an inhibitor of ecto-5'-nucleotidase) completely abolished the increased coronary hyperemic flow and improvements of myocardial contractile function due to AICA riboside. Thus it was concluded that AICA riboside improves the contractile dysfunction that follows a brief period of ischemia via adenosine-dependent mechanisms.

The detection of technical failures in perfused heart with ischemia and reperfusion by epicardial NADH fluorescence

This study documents the value of continuous observation of nicotinamide adenine dinucleotide (NADH) fluorescence (NADH-F). NADH-F monitoring is used to identify ischemic regions for the recognition of minor technical failures associated with ischemia and reperfusion experiments in the isolated perfused heart system. The visualization of NADH-F is possible by simply irradiating the heart with ultraviolet light. Rat hearts, in the working-heart mode, were subjected to occlusion/reperfusion of the left coronary artery, and analyzed. The perfusate was filtered through a 5 micron pore membrane. Out of 281 hearts which were judged to be free of technical failures by conventional physiological indices (heart rate greater than 200/min, cardiac output greater than 34 ml/min, and coronary flow 9-14 ml/min), 43 (15%) disclosed an abnormal NADH-F area prior to the coronary intervention. During coronary intervention, 29 technical failures were detected as indicated by sparse NADH-F distribution with occlusion, delayed disappearance of NADH-F upon reperfusion, or the exhibition of an abnormal NADH-F region unassociated with the coronary artery supply area. These technical failures are not detectable without the use of NADH-F, although the actual number of failures detected may depend on the skill of the operator. We recommend NADH-F monitoring for any preparations which do not contain hemoglobin, since NADH-F is an intrinsic probe for ischemia and is easily applicable to a variety of experiments.

Plasma and urinary metabolites of efonidipine hydrochloride in man

1. The plasma and urinary metabolite profiles of efonidipine hydrochloride, a new dihydropyridine calcium antagonist, have been examined in six healthy male volunteers after oral dosing. 2. Unchanged drug in plasma was determined by hplc-ms. Five metabolites in plasma and five metabolites and unchanged drug in urine were identified by hplc. 3. The main plasma metabolites were N-dephenylated-efonidipine and deaminated-efonidipine. 4. No significant amount of unchanged drug was excreted in urine. In the urine collected for 24 h after a oral dosing, 1.1% of the dose was excreted as deaminated-efonidipine, and 0.5% as a pyridine analogue of deaminated-efonidipine.

Induction of transient airway hyperresponsiveness by exposure to 4 ppm nitrogen dioxide in guinea pigs

In the present study, we investigated (1) whether airway responsiveness to inhaled histamine-aerosol could be induced during 7-d exposure of guinea pigs to 4 ppm NO2 and, if so, (2) whether thromboxane A2 may be involved in such increase. Female Hartley guinea pigs were divided into 6 groups (n = 15/group). Three groups were exposed to filtered air and the other 3 groups were exposed to NO2 for 1, 3, or 7 d (24 h/d). Baseline specific airway resistance (SRaw0) did not change significantly after exposure to 4 ppm NO2 or air. Airway responsiveness was determined 1 wk before the beginning of exposure and on the day of termination of the exposure. Prior to exposure to NO2, the EC200His, the concentrations of inhaled histamine necessary to double SRawNaCl (SRaw after inhalation of 0.9% NaCl), were 1.07 +/- 0.20, 1.30 +/- 0.20, and 1.01 +/- 0.18 mM for the 3 groups later given NO2 for 1, 3, and 7 d, respectively. Following exposure to NO2 for 1, 3, or 7 d, EC200His values were 1.42 +/- 0.25, 0.66 +/- 0.10 (p < .05), and 1.05 +/- 0.22 mM, respectively. These results show that 7-d exposure to 4 ppm NO2 induced a significant increase in airway responsiveness on d 3. Exposure to air had no significant effect on the airway responsiveness. This transient hyperresponsiveness was inhibited by a specific inhibitor of thromboxane synthetase, OKY 046. These results indicated that (1) a lower concentration (4 ppm) of NO2 than that previously reported can induce transient hyperresponsiveness in guinea pigs during appropriate long-term exposure, and (2) thromboxane A2 may play an important role in this transient airway hyperresponsiveness.