Delayed rectifier K+ current of dog bronchial myocytes: effect of pollen sensitization and PKC activation.
The properties of delayed rectifier K+ current [IK(dr)] of canine airway smooth muscle cells isolated from small bronchi and its modulation by protein kinase C (PKC) were studied by whole cell patch clamp. IK(dr) activated positive to -40 mV, with half-maximal activation at -16 +/- 1.2 mV (n = 15) and average current density of 31 +/- 2.6 pA/pF (n = 15) at +30 mV. The capacitive surface area, current density, and voltage dependence of activation of IK(dr) of myocytes of ragweed pollen-sensitized dogs were not different from age-matched control dogs. However, the sensitization reduced the availability of IK(dr) between -40 and -20 mV due to a hyperpolarizing shift in the voltage dependence of steady-state inactivation (-29.9 +/- 1.2 in sensitized versus -26.0 +/- 0.7 mV in control dogs, n = 9 and 11, respectively; P < 0.05). PKC activation with diacylglycerol analog or phorbol ester depressed IK(dr) amplitude, whereas an inactive diacylglycerol analog had no effect. The hyperpolarizing shift in voltage dependence of inactivation and/or modulation of IK(dr) by PKC may be two mechanisms that contribute to the enhanced reactivity of bronchial tissues from ragweed pollen-sensitized dogs.
Smooth Muscle Research Group, Faculty of Medicine, University of Calgary, Calgary, Alberta T2N 4N1.
G J
GJ
Waldron
S B
SB
Sigurdsson
E A
EA
Aiello
A J
AJ
Halayko
N L
NL
Stephens
W C
WC
Cole
D000818:Animals; D000831:Animals, Newborn; D001980:Bronchi / Q000276:immunology / Q000502:physiology*; D002118:Calcium / Q000494:pharmacology; D002478:Cells, Cultured; D002614:Chelating Agents / Q000494:pharmacology; D051668:Delayed Rectifier Potassium Channels; D004285:Dogs; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D004553:Electric Conductivity; D004789:Enzyme Activation; D007114:Immunization; D008564:Membrane Potentials; D018408:Patch-Clamp Techniques; D015240:Phorbol 12,13-Dibutyrate / Q000494:pharmacology; D011058:Pollen; D015221:Potassium Channels / Q000502:physiology*; D024642:Potassium Channels, Voltage-Gated; D011493:Protein Kinase C / Q000378:metabolism*; D019789:Tetraethylammonium / Q000494:pharmacology
D002614:Chelating Agents; D051668:Delayed Rectifier Potassium Channels; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D015240:Phorbol 12,13-Dibutyrate; D004533:Egtazic Acid; D019789:Tetraethylammonium; D011493:Protein Kinase C; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; D002118:Calcium