Effect of dl-praeruptorin A on desmin and vimentin content in rat ischemia/reperfusion myocardiocytes.

BACKGROUND: Intermediate filament (IF) proteins have been thought to play a role in nuclear centration, organelle movement and maintenance of cell shape. dl-praeruptorin A (Pd-Ia), a novel Ca2+-influx blocker and K+-channel opener isolated from Chinese traditional herbal medicine Qian-Hu, has been demonstrated to inhibit expression of apoptosis related proteins and reduce the level of proinflammatory factors in ischemia/reperfusion myocardiocytes. Morphologically, whether Pd-Ia effects myocardiocyte IFs remains unclear. The purpose of this study was, for the first time, to evaluate the in vivo effects of Pd-Ia on IF desmin and vimentin content in order to further explore its cardioprotection against ischemia and elucidate its mechanism of action. METHODS: Rats underwent a 30 minutes coronary occlusion followed by 120 minutes reperfusion. Assessment of desmin and vimentin content of myocardiocytes was performed by immunohistochemistry, Western blot, Hematoxylin-Eosin staining and densitometry. RESULTS: Pretreatment with i.v. infusion of Pd-Ia prior to ischemia significantly increased desmin and vimentin content and alleviated defects caused by the ischemia/reperfusion insult, e.g. with Pd-Ia at a dose of 0.5 or 1.0 mg/kg, integrated density values of desmin were increased from 61 478 +/- 10 074 to 177 408 +/- 10 395 and 195 784 +/- 20 057, and vimentin from 59 189 +/- 19 853 to 164 781 +/- 19 543 and 185 696 +/- 20 957 (P < 0.01, vs placebo), respectively. The recovery of desmin seemed to be stronger and appeared earlier than that of vimentin. CONCLUSION: Pd-Ia protectively increased IF desmin and vimentin content in ischemia/reperfusion myocardiocytes, which might be partially responsible for its cardioprotection against ischemia.

Effects of dl-praeruptorin A on nucleus factor-kappaB and tumor necrosis factor-alpha expression in ischemia-reperfusion hearts.

AIM: To study the effects of dl-praeruptorin A (Pd-Ia) on nucleus factor-kappaB (NF-kappaB) activativity and tumor necrosis factor-alpha (TNF-alpha) expression in ischemia-reperfusion (I/R) myocardium. METHODS: Langendorff's isolated rat heart was subjected to a 10-min ischemia followed by a 30-min reperfusion. NF-kappaB activity in nucleus was analyzed by Sandwich Enzyme-Linked Immunosorbent Assay (ELISA). TNF-alpha level in cytoplasm was measured by radioimmunoassay. Infiltration of neutrophils was observed using Hematoxylin-Eosin staining under optical microscope. RESULTS: Pd-Ia 1.0 micromol/L with 30-min preventive perfusion decreased NF-kappaB activity from 0.98+/-0.13 to 0.65+/-0.17 (P<0.05 vs solvent) and down-regulated TNF-alpha expression from 13.7+/-6.1 microg/L to 9.4+/-2.7 microg/L (P<0.01 vs solvent) under conditions with increase of coronary flow, negative inotropic action, inhibition of creatine kinase and without chronotropic action, whereas, infiltration of neutrophils was mild. CONCLUSION: Pd-Ia inhibited NF-kappaB activativity in I/R myocardium and led to down-regulation of TNF-alpha expression, which might be one of molecular mechanisms of Pd-Ia in cardioprotection.

Effects of tetrandrine on smooth muscle contraction induced by mediators in pulmonary hypertension.

AIM: In attempt to characterize tetrandrine on pulmonary hypertension, biological activities induced by a range of mediators implicated in the pathogenesis of pulmonary hypertension were investigated. METHODS: Pulmonary artery rings and tracheal segments were contracted with couples of bioactive substances in which a series experiments including effects of tetrandrine on calcium agonist, endothelin, thromboxane A2, angiotensin II, neuropeptide Y, histamine, 5-methyl furmethide were performed, the influences of tetrandrine in the concentration of 1 to 30 micromol/L were investigated. RESULTS: Tetrandrine inhibited calcium agonist BayK8644, endothelin-1 and thromboxane A2 mimetic U46619, angiotensin II- and neuropeptide Y-induced contractile responses with depression of the maximal contraction of pulmonary artery rings in a varying extent. Tetrandrine inhibited leukotriene E4-induced concentration-response curve in a competitive antagonist manner with a pKB of (5.29+/-0.11) without any influence leukotriene C4, leukotriene D4, histamine, and 5-methyl furmethide induced contractile responses of guinea pig trachea. CONCLUSION: Tetrandrine may produce multiple pharmacological effects against calcium channel antagonist, U46619, endothelin-1,angiotension II, and neuropeptide Y induced vasoconstriction in rat pulmonary arteries in varying extent and inhibition of leukotriene E4 rather than C4, D4, histamine, and 5-methyl furmethide induced contractile responses on rat tracheal segments. These pharmacological characteristics are considered to contribute to its antihypertensive action during pulmonary hypertension.

Effects of dl-praeruptorin A on interleukin-6 level and Fas, bax, bcl-2 protein expression in ischemia-reperfusion myocardium.

AIM: To investigate the effects of dl-praeruptorin (Pd-Ia) on interleukin-6 (IL-6) level and apoptosis-related protein expression in ischemia-reperfusion myocardium. METHODS: Left anterior descending coronary artery was subjected to 30 min ischemia followed by 120 min reperfusion in open-chest anesthetized rats. Serum IL-6 level was measured by radioimmunoassay. Apoptosis-related protein Fas, bax, and bcl-2 expression was detected by immunohistochemistry and computer image analysis system. Infiltration of neutrophils was observed using Hematoxylin-Eosin staining under optical microscope. RESULTS: Pd-Ia 2.0 mg/kg iv lowered serum IL-6 level and Fas, bax, bcl-2 expression under conditions with hypotension and without changes on heart rate, but increased the ratio of bcl-2/bax. There existed a close linearity and positive correlation between IL-6 level and Fas, bax, bcl-2 expression. Whereas, the infiltration of neutrophils was mild. CONCLUSION: Pd-Ia elicits a novel target in the therapeutic prevention of postischemic cardiomyocyte death. The reason might be associated with modulating the expression of some immediate-early genes including IL-6, Fas, bax, and bcl-2 in ischemia-reperfusion myocardium.