Decreased amplitude of Ca²⁺i elevation induced by menthol in pulmonary arterial smooth muscle cells of pulmonary hypertensive rats / 生理学报

The study was designed to explore the alteration of intracellular calcium concentration ([Ca²⁺]i), induced by transient receptor potential melastatin 8 (TRPM8) channel-specific agonist menthol, in pulmonary arterial smooth muscle cells (PASMCs) between control and pulmonary hypertensive (PH) rats. PH rat models were established by means of chronic hypoxia (CH) and monocrotaline (MCT) injection, respectively. PASMCs from control and PH rats were cultured. The change of [Ca²⁺]i in PASMCs induced by menthol, and the effect of TRPM8 channel-specific antagonist BCTC on the change of [Ca²⁺]i, were observed. Cellular localization of TRPM8 was examined by using immunohistochemistry. Results showed that menthol increased [Ca²⁺]i in the control PASMCs both in Ca²⁺ -normal and Ca²⁺ - free Tyrode's solutions, and at the same time BCTC could inhibit these two kinds of elevations. Compared with the control group, elevations of [Ca²⁺]i were decreased notably in CH- and MCT-pretreated PASMCs superfused with 2 mmol/L Ca²⁺ - or 0 Ca²⁺ -Tyrode's solutions. Immunohistochemical localization experiments showed that the whole PASMCs were dyed brown except for the nucleus. This study verified that TRPM8 exists both in membrane and sarcoplasmic reticulum of PASMCs. In addition, CH- and MCT-pretreatment could independently down-regulate the Ca²⁺ influx and Ca²⁺ release mediated by TRPM8 channel.

The application of isoprenaline provocation test on rat model of alcoholic cardiomyopathy / 中国应用生理学杂志

<p><b>OBJECTIVE</b>To study a simple and reliable method to produce the rat model of alcoholic cardiomyopathy, evaluating the model with isoprenaline provocation test (IPT) and morphological indicators.</p><p><b>METHODS</b>Adult male rats were intragastrically infused of wine (52% v/v) at 20 g/(kg x d) for 15 days with the general condition, the change of eating amount and weight being observed. The levels of mean left ventricle systolic pressure (mLVSP), mean left ventricle diastolic pressure (mLVDP), mean left ventricle pressure (mLVP), heart ratio (HR), maximal rise velocity of left ventricular pressure (+ dp/dtmax), maximal fall velocity of left ventricular pressure (- dp/dtmax) and the reaction of isoprenaline were examined by left ventricular cannulation, and the morphological change was observed with optical microscope and transmission electron microscopy.</p><p><b>RESULTS</b>Both diastolic and systolic function of the model rats was lower than that of the control group as well as the cardiac energy reserve induced by IPT. Pathological observation demonstrated myocardial hypertrophy, myocardiocyte necrosis and infiltration of inflammatory cells. The transmission electron microscopy showed that mitochondria became enlarged or crimpled with fused or disappeared cristae and myofibrils dissolved and fractured.</p><p><b>CONCLUSION</b>The adult male SD model rats exhibit diabetic cardiomyopathy by intragastric infusion of wine (52% v/v) at 20 g/(kg x d) for 15 days. IPT can induce the cardiac energy reserve and evaluate that accurately, displaying the hidden heart dysfunction.</p>

The effect of different dose of verapamil and propranolol in kalium cardioplegia on the function of immature rat heart / 中国应用生理学杂志

<p><b>AIM</b>To explore the appropriate dose of the verapamil and propranolol in kalium cardiaplegia (KVP) by observation of the effect on the function of ischemic immature rat heart and compared with ST. Thomas II cardiaplegia.</p><p><b>METHODS</b>48 isolated hearts from Sprague-Dawley rats of 60 to approximately 80 g body weight, 22 +/- 2 days, male or female are perfused by Langendorff method for 20 min, and assigned to 1 of the following 6 groups (n = 8): control (CON), continuously perfused for 150 min. Ischemia/reperfusion (I/R), perfused with Locke's solution without glucose and oxygen equilibration for 3 min then no perfusion 27 min, repeated 3 cycles (ischemia for 90 min), followed by reperfusion for 60 min. Ischemia protected with ST. Thomas II cardioplegia (ST), each 3 min perfusion with ST. Thomas II cardioplegia during ischemia. Ischemia protected with three dose KVP cardioplegia (L, M, and H), perfused with ST. Thomas II cardioplegia containing verapamil and propranolol (x 10(-7) mol L(-1)) respectively 2.0, 0.34 (L), 6.8, 1.1 (M), 20,3.4 (H) during each 3 min perfusion of ischemia. Heart rate (min (-1), tens on(g), contraction force(g), peak systolic velocity (g.s-1), peak diastole velocity (g.s-), coronary flow (ml x min(-1 ), re-beat time (s) were monitored during the ischemia/ reperfusion.</p><p><b>RESULTS</b>Compared to CON group, heart tension was rose when ischemia for 40 min and kept higher and could not rebeat after reperfusion in I/R group, In ST group, heart tension was rose after ischemia for 60 min and could re-beat but the pulse was weaker. Compared with ST group, KVP decreased the ischemic cardiac tension in dose dependently and the re-beat was stronger in L, M, and H groups. While compared with CON group, in L group, heart tension was rose when ischemia for 60 min and the re-beat was weaker. In H group, the heart tension was maintained lower when ischemia for 40 min and the re-beat was delay and weaker. Only in M group, heart tension was maintained stable during ischemia for 90 min and re-beat was stronger after reperfusion.</p><p><b>CONCLUSION</b>Kalium cardiaplegia containing verapamil 6.8 x 10(-7) mol x L(-1) and propranolol 1.1 x 10(-7) mol x L(-1) has the best effect to protect the immature heart from ischemic injury.</p>