2.2. Buffers and Solutions

For the transport and preparation of the smooth muscle strips and for the incubation in the organ bath, KH was used (in mmol/L: NaCl 115.0 (VWR International GmbH, Darmstadt, Germany), 4.7 KCl, 2.5 CaCl₂, 1.2 MgCl₂, 1.2 NaH₂PO₄, 25.0 NaHCO₃ (all Carl Roth GmbH & Co. KG, Karlsruhe, Germany) and 11.0 glucose (VWR International GmbH, Darmstadt, Germany)). Before use, the buffer was gassed with carbogen (95% O₂, 5% CO₂) under constant temperature conditions (38 °C). The final pH of the buffer was 7.4. Furthermore, two buffer variations were used for the experiments: a calcium-free buffer (in mmol/L: NaCl 115.0 (VWR International GmbH, Darmstadt, Germany), 4.7 KCl, 1.2 MgCl₂, 1.2 NaH₂PO₄, 25.0 NaHCO₃ (all Carl Roth GmbH & Co. KG, Karlsruhe, Germany) and 11.0 glucose (VWR International GmbH, Darmstadt, Germany)) and a potassium-enriched buffer, containing potassium chloride instead of sodium chloride (in mmol/L: 123.4 KCl, 2.5 CaCl₂, 1.2 MgCl₂, 1.2 NaH₂PO₄, 25.0 NaHCO₃ (all Carl Roth GmbH & Co. KG, Karlsruhe, Germany) and 11.0 glucose (VWR International GmbH, Darmstadt, Germany)).