MATERIALS AND METHODS
Isolation of human myocytes: Atrial tissue samples were obtained from the right atrial appendage of patients undergoing coronary bypass surgery, and ventricular subepicardial samples were taken from the free left ventricular wall of explanted hearts from transplant recipients. Tissue specimens were transported to the laboratory in either Tyrode’s solution (inmM: NaCl 127, KCl5.4, MgCl2 1.1,CaCl2 1.8,NaH2PO4 0.4 and NaHCO3 22.0, saturated with 95% oxygen and 5% carbon dioxide to give pH 7.4) or cold cardioplegic solution (Custodial, Kohler Chemie, Alsbach, Germany). The enzymatic digestion procedure has been described previously . Briefly, the tissue was chopped into chunks of approximately 1 mm3 in nominally calcium-free solution. The chunks were then incubated under gentle agitation with collagenase IA-containing solution (1.0 mg/mL, Sigma, Munchen, Germany) until rod-shaped, striated cells were dissociated.The cells were harvested into enzyme-free solution, and the calcium concentration was raised to 0.5 mM before storage.
Measurement of membrane currents: For measurement of action potentials and membrane currents, the single-electrode whole cell current clamp and voltage clamp techniques were applied using a List EPC-7 amplifier (List Instruments, Darmstadt, Germany). Clamp software (Axon Instruments, Foster City, California, USA) was used for experimental control and data analysis. Electrodes pulled from filamented borosilicate glass had tip resistances of 2 to 4 MQ; when filled with electrode solution (in mM: KCl 130, MgCl2 4, CaCl2 5, HEPES 10, EGTA 10, Na2-ATP4, pH 7.3; free [Ca2+] 50nM, free [Mg2+] 300 pM). You can be sure this pharmacy will offer the finest quality drugs you need, so buying cheap nolvadex cialis professional will always be safe and very pleasant for you as a customer and patient.