Hydrogen peroxide-induced enhancement of prostanoid release and myocardial damage by its washout in isolated rat heart  Takao Okada, Katsuhiko Asanuma, Tai Nakamura, Rikuo Ochi  Pathophysiology  Volume 6, Issue 1, Pages 27-33 (April 1999) DOI: 10.1016/S0928-4680(98)00034-0

Fig. 1 Experimental protocols. Time-matched control hearts (top: n=9) were perfused for 65 min under aerobic conditions without any treatment. At various times during perfusion, coronary effluent was collected and its prostanoid (PG: 15, 20, 30, 45 and 50 min), NO (15, 20, 30, 45 and 50 min) and GOT activity (15, 30, 45, 55 and 65 min) levels were measured. Experimental hearts (middle) were perfused for 30 min with H2O2-containing Krebs solution under aerobic conditions after a 15 min stabilization period, followed by washout of H2O2 with normal Krebs solution. Four hearts were subjected to prolonged (50 min) perfusion with 200 μM H2O2 with no subsequent washout (bottom). The PG, NO and GOT activity levels at the same time points as those for the time-matched controls were determined. Pathophysiology 1999 6, 27-33DOI: (10.1016/S0928-4680(98)00034-0)

Fig. 2 H2O2-induced changes in left ventricular pressure. Top to bottom: time matched-control (A, n=9), 70 μM (B, n=9), 200 μM (C, n=9) and 700 μM H2O2 (D, n=4). In panels B–D, the shadowing indicates H2O2 perfusion. H2O2 depressed left ventricular pressure development (•) and elevated end diastolic pressure (○) concentration-dependently. The upper open numbers on the abscissa represent the minutes after the initiation of perfusion of the time-matched controls, the lower solid numbers and open numbers indicate the minutes after the onset of H2O2 perfusion and after washout, respectively. Pathophysiology 1999 6, 27-33DOI: (10.1016/S0928-4680(98)00034-0)

Fig. 3 H2O2-induced changes in coronary perfusion pressure. Perfusion with 200 μM H2O2 (•) (H2O2 200, n=9) reduced the coronary perfusion pressure transiently but significantly (P<0.05), after which, it increased to a significantly higher level than that of the time-matched control (○) (TC, n=9) and washout of H2O2 did not reverse this effect. A lower concentration of H2O2, 70 μM (▴) (H2O2 70, n=9), reduced the coronary perfusion pressure during the early phase similarly, but no pressure elevation during or after H2O2 perfusion occurred. Numbering on the abscissa as for Fig. 2. Pathophysiology 1999 6, 27-33DOI: (10.1016/S0928-4680(98)00034-0)

Fig. 4 H2O2-induced changes in prostanoid release. Prostanoids released into the coronary effluent were quantified by GC/MS (n=9 each). PGD2, PGE2, PGF2α, and TXA2 release increased significantly (**P<0.01, *P<0.05) during the early phase of 200 μM H2O2 perfusion. The open squares in each panel represent release of the corresponding prostanoid by the time-matched control hearts. Numbering on the abscissa as Fig. 2. Pathophysiology 1999 6, 27-33DOI: (10.1016/S0928-4680(98)00034-0)

Fig. 5 H2O2-induced changes in PGI2 release. PGI2 release increased significantly after perfusion with 200 μM H2O2 (•) (H2O2 200, n=9). The effect of H2O2 on PGI2 release was concentration-dependent: 70 μM H2O2 (▴) (H2O2 70, n=9) increased significantly, but to a lesser extent than 200 μM. The open circles represent PGI2 release by the time-matched control (TC). Numbering on the abscissa as for Fig. 2. Pathophysiology 1999 6, 27-33DOI: (10.1016/S0928-4680(98)00034-0)

Fig. 6 Effect of H2O2 on NO release. The NO released into the coronary effluent was quantified by an ozone chemiluminscence method. NO release did not change significantly during 200 μM perfusion or the subsequent washout period (•) (n=9) in comparison with that by the time-matched controls (○) (n=9). Numbering on the abscissa as for Fig. 2. Pathophysiology 1999 6, 27-33DOI: (10.1016/S0928-4680(98)00034-0)

Fig. 7 GOT release induced by H2O2 perfusion. GOT release did not increase during perfusion with 200 μM H2O2 (•) (n=9), but it increased gradually as the washout of H2O2 progressed, reaching a significantly higher level than that of the time-matched control (○) (n=9). The solid triangles represent GOT release, which did not increase, during perfusion with 200 μM H2O2 for 50 min without washout (n=4). Numbering on the abscissa as for Fig. 2. Pathophysiology 1999 6, 27-33DOI: (10.1016/S0928-4680(98)00034-0)

Fig. 8 Effects of indomethacin on H2O2-induced changes in coronary perfusion pressure (top panel) and GOT release (bottom panel). Administration of 30 μM indomethacin (IM) (○) inhibited the H2O2-induced initial transient decrease in coronary perfusion pressure but showed no effect on the later coronary vasoconstriction. Although prostanoid release was suppressed almost completely with indomethacin, the washout-induced increase in GOT release was little affected. The closed circles of each panel represent mean values without indomethacin which are identical to those in Fig. 3 and Fig. 7, respectively. Numbering on the abscissa as for Fig. 2. Pathophysiology 1999 6, 27-33DOI: (10.1016/S0928-4680(98)00034-0)