title: Effects of epinephrine on electrical properties of Madin-Darby canine kidney cells.
abstract: The present study has been performed, to test for the influence of epinephrine on the potential difference across the cell membrane (PD) of Madin-Darby canine kidney (MDCK) cells. Under control conditions, mimicking the in vivo situation, PD averages - 53.3 +/- 0.9 mV (n = 37). Increasing extracellular potassium concentration from 5.4 to 10 and 20 mmol/l depolarizes the cell membrane by +4.3 +/- 0.4 mV (n = 5) and +15.8 +/- 1.2 mV (n = 5), respectively. The application of 1 mumol/l epinephrine leads to sustained hyperpolarization of the cell membrane to -71.5 +/- 0.7 mV (n = 37). In the presence of epinephrine, increasing extracellular potassium concentration from 5.4 to 20 mmol/l depolarizes the cell membrane by +30.6 +/- 0.2 mV (n = 5); 1 mmol/l barium depolarizes the cell membrane by +14.8 +/- 0.7 mV (n = 20) and abolishes the effect of step increases of extracellular potassium concentration from 5.4 to 10 mmol/l. In the presence of barium, epinephrine leads to a transient hyperpolarization by -31.2 +/- 1.2 mV (n = 18). During this transient hyperpolarization, the cell membrane is sensitive to extracellular potassium concentration despite the continued presence of barium; 10 mumol/l verapamil depolarizes the cell membrane to -41.0 +/- 2.6 mV (n = 11). In the presence of verapamil, the hyperpolarizing effect of epinephrine is only transient; 10 mumol/l phentolamine depolarizes the cell membrane by +3.0 +/- 0.6 mV (n = 8). In the presence of phentolamine, the effect of epinephrine is virtually abolished (+0.4 +/- 0.6 mV, n = 8); 1 mumol/l isoproterenol depolarizes the cell membrane by +2.8 +/- 0.8 mV (n = 8).(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology; D004285:Dogs; D004553:Electric Conductivity; D004594:Electrophysiology; D004837:Epinephrine / Q000494:pharmacology*; D007668:Kidney / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D009994:Osmolar Concentration; D010646:Phentolamine / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D014700:Verapamil / Q000494:pharmacology
chemical_list: D014700:Verapamil; D011188:Potassium; D002118:Calcium; D004837:Epinephrine; D010646:Phentolamine