Y Matsukura

Clinical Research Hospital, Tokyo, Edo, Tōkyō, Japan

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Publications (8)7.48 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: To investigate the contractility of pulmonary arterial smooth muscle and the relation between pulmonary hypertension and endothelium-derived relaxing factor in canine heartworm disease. 18 noninfected control and 9 heartworm-infected dogs. Mean pulmonary arterial blood pressure was measured in vivo, and tension of pulmonary arterial strips was measured by use of the isometric tension method. After phenylephrine (10(-5)M)-induced contraction of the pulmonary vascular smooth muscle, carbamylcholine chloride (CCh, 10(-6)M) caused more relaxation of the vascular smooth muscle of noninfected, dogs than that of heartworm-infected dogs. Furthermore, the degree of CCh-induced relaxation was inversely correlated with mean pulmonary arterial blood pressure in the noninfected and the heartworm-infected dogs. The CCh-induced relaxation was inhibited by pretreatment with NG-nitro-L-arginine methyl ester hydrochloride (10(-5)M), and in reversed dose-dependent manner by L-arginine (10(-4) to 3 x 10(-2)M). Sodium nitroprusside (10(-8) to 10(-5)M) caused a dose-dependent relaxation in all vessels, and there was no significant difference in the relaxation responses in both groups except at 10(-7)M for vessels with intact endothelium from noninfected dogs. The depression of endothelium-dependent relaxation is correlated with the pulmonary arterial blood pressure in heartworm-infected dogs, suggesting that the decrease is one of the essential factors for the genesis of pulmonary hypertension in canine filariasis.
    American Journal of Veterinary Research 03/1997; 58(2):171-4. · 1.35 Impact Factor
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    ABSTRACT: The longitudinal distribution of pulmonary vascular compliance was evaluated in isolated canine lung lobes using arterial-(AO), venous-(VO), and double-occlusion (DO) techniques. Total vascular compliance (Ctau) was separated into pulmonary arterial (Ca) and venous compliance (Cv) in lumped model of pulmonary circulation. Under constant pulmonary venous pressure (Pv) at 5 mmHg, blood inflow to the lobe (Q) was gradually increased by changing pulmonary arterial pressure (Pa) from 10 to 22 mmHg at 4 mmHg ranges. Changes in vascular blood volume (deltaV) with each increment in Q were determined by decreased reservoir blood volume of perfusion system. DO was performed at each level of Q and allowing all vascular pressures to equilibrate at the same static pressure (Ps), which was equal to the compliance-weighted average pressure in the circulation. Ctau was obtained from the slope of the relationship between Ps and deltaV. When Pa and Pv were 14 and 5 mmHg, AO, VO, and DO were performed to measure pressures at Ca (Pca) and Cv (Pcv) and Ps. The arterial-to-venous compliance ratio (Ca/Cv) was evaluated using Pca, Pcv, and Ps measurements. Ctau was 0.113 +/- 0.012 ml/kg/mmHg. Ca/Cv was 0.30. Ca and Cv were 0.026 +/- 0.013 and 0.087 +/- 0.007 ml/kg/mmHg, respectively. These data demonstrated the usefulness of AO, VO, and DO techniques in evaluating the longitudinal distribution of compliance in canine pulmonary vasculature.
    Journal of Veterinary Medical Science 02/1996; 58(1):41-6. · 0.88 Impact Factor
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    ABSTRACT: The effects of dopamine and dobutamine in various doses on liver oxygen supply-uptake relationship were studied in 12 mongrel dogs. Dopamine 3 and 7 micrograms/kg/min infusion rates and dobutamine 5 micrograms/kg/min infusion rate did not produce any changes in total liver oxygen delivery. On the contrary, total liver oxygen delivery was increased at the 15 micrograms/kg/min dopamine in fusion rate and dobutamine 10 and 15 micrograms/kg/min infusion rates. The ratio of total liver oxygen delivery to the systemic oxygen delivery was increased at the 15 micrograms/kg/min dopamine infusion rate. Liver oxygen extraction ratio was decreased at the 15 micrograms/kg/min dopamine infusion rate and at the same rate of dobutamine. These decreases were due to the increases in oxygen delivery while both oxygen uptakes were avariant from control levels. The results of this study demonstrated that high dose of dopamine (15 micrograms/kg/min) and medium and high doses of dobutamine (10 and 15 micrograms/kg/min) should be useful to increase the liver oxygen delivery. However, these increases in liver oxygen delivery during dopamine and dobutamine infusion were not associated with an improvement in liver oxygen metabolism, since liver oxygen uptake was not changed.
    Journal of Veterinary Medical Science 05/1995; 57(2):287-91. · 0.88 Impact Factor
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    ABSTRACT: Hepatic hemodynamics and the liver oxygen supply-uptake relationship, in response to eating, were investigated in a chronically catheterized conscious dog method. Portal venous pressure was significantly increased after eating, however was within the normal range reported previously. Hepatic venous pressure correlated well with portal venous pressure throughout the experiment, therefore, the pressure gradient of the portal system was unchanged. Hepatic venous oxygen content, correlated well with liver oxygen extraction, was unchanged after eating. Therefore, it is possible to assume that liver oxygen supply-uptake relationship is well maintained during digestion of food.
    Journal of Veterinary Medical Science 05/1995; 57(2):323-6. · 0.88 Impact Factor
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    ABSTRACT: The effects of indomethacin on liver blood flow and oxygen supply-uptake relationship were investigated using a right heart bypass technique. Portal venous blood flow was decreased by the mesenteric vascular effects of indomethacin, which produce intense mesenteric vasoconstriction. Hepatic arterial blood flow was increased and therefore, total liver blood flow was not significantly changed after indomethacin administration. Portal venous oxygen delivery was significantly decreased by reductions in both portal venous blood flow and portal venous oxygen content. Total liver oxygen delivery, however, was not changed after indomethacin administration. This response was caused by a large increase in hepatic arterial oxygen delivery. Liver oxygen uptake and liver oxygen extraction ratio were not changed after indomethacin administration. We conclude, therefore, that total liver blood flow and oxygen delivery were well maintained, even if the mesenteric vascular effects of indomethacin decreased both portal venous blood flow and portal venous oxygen delivery.
    Journal of Veterinary Medical Science 05/1995; 57(2):193-7. · 0.88 Impact Factor
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    ABSTRACT: The selective effects od dopamine and dobutamine in various doses on liver circulation were studied in 12 mongrel dogs. Dopamine increased portal flow but decreased hepatic arterial flow markedly as infusion rate of dopamine increased. Dopamine 3 micrograms/kg/min infusion rate produced vasodilation in mesenteric vascular bed and the portal flow ratio to cardiac output was significantly increased. Dobutamine increased both portal and hepatic arterial flows at the 5 and 10 micrograms/kg/min dobutamine infusion rates, and decreased hepatic arterial flow at the 15 micrograms/kg/min dobutamine infusion rate. Both dopamine and dobutamine increased total liver flows, however, total liver flow ratio to cardiac output was not increased. Pressure gradient of portal system was not changed during dopamine and dobutamine infusion, since both portal venous pressure and hepatic venous pressure were avariant from control values. These findings suggest that congestive hyperemia was not occurred in intrahepatic portal vascular system when portal flows were increased during dopamine and dobutamine infusion. The results of this study demonstrate that both dopamine and dobutamine did not produce selective increases in total liver blood flow. In addition, both agents should be safe to use to the normal liver patient; total liver blood flow did not decrease and intrahepatic congestive hyperemia was not occurred when portal flow was increased.
    Journal of Veterinary Medical Science 05/1995; 57(2):293-7. · 0.88 Impact Factor
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    ABSTRACT: To compare the cardiovascular effects of dibutyryl cyclic AMP (DBcAMP) and milrinone, we used the right heart bypass method in intact anesthetized dogs. The preload of the left ventricle was maintained constant throughout the experiment. Therefore, the effects of DBcAMP and milrinone on cardiac contractility and afterload of the left ventricle were investigated respectively without preload influence. DBcAMP and milrinone exhibited marked positive chronotropic-, positive inotropic-, vasodilative- and diuretic-activity. DBcAMP expressed these effects gradually and continuously, whereas milrinone expressed its pharmacological actions rapidly, but for a short duration of time. Both the afterload-reducing and the cardiac contractile force-enhancing activities of DBcAMP were longer lasting than those of milrinone. Mean arterial pressure was not altered by DBcAMP infusion, whereas it was increased significantly (p < 0.05) by milrinone infusion. The results of this study suggested that DBcAMP appeared to be indicated when there is a need to increase cardiac output by reducing afterload and increasing cardiac contractile force gradually and continuously. On the other hand, milrinone would seem to be indicated when the goal is to raise blood pressure rapidly and to increase cardiac output simultaneously.
    Journal of Veterinary Medical Science 11/1994; 56(5):923-8. · 0.88 Impact Factor
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    ABSTRACT: To analyze longitudinal distribution of pulmonary vascular resistance, we proposed a five element lumped model which partitioned pulmonary circulation into pulmonary arterial, middle and pulmonary venous segment. The validity and anatomical correlation of the model were tested in an isolated, perfused, canine lung lobe preparation with inflow/outflow occlusion techniques. With arterial occlusion, pulmonary arterial pressure fell rapidly and then exponentially. With venous occlusion, pulmonary venous pressure rose suddenly and then exponentially. Theoretical pressure profiles produced by computer simulation of the model well approximated the general characteristics of the experimental traces. Serotonin increased the pressure gradient across the pulmonary arterial segment (delta Pa), whereas histamine increased the gradient across the pulmonary venous segment (delta Pv). Neither drug altered the gradient across the middle segment (delta Pm). The results suggest that the lumped model is a useful concept to understand the longitudinal distribution of pulmonary vascular resistance, and that delta Pa, delta Pm and delta Pv reflect the resistance distribution of anatomical pulmonary arteries, alveolar vessels and pulmonary veins, respectively.
    Journal of Veterinary Medical Science 03/1994; 56(1):71-6. · 0.88 Impact Factor

Publication Stats

11 Citations
7.48 Total Impact Points

Institutions

  • 1994–1997
    • Clinical Research Hospital, Tokyo
      Edo, Tōkyō, Japan
  • 1995
    • Tokyobay UrayasuIchikawa Medical Center
      Urayasu, Tōkyō, Japan