An ATP-sensitive potassium channel blocker decreases diaphragmatic circulation in anesthetized dogs.
The goal of this study was to determine whether in the dog ATP-sensitive K+ channels blocked with glibenclamide affect diaphragmatic blood flow [phrenic arterial blood flow (Qpa)] during both spontaneous breathing at rest and increased diaphragmatic activity. A control group (no glibenclamide; n = 4) and an experimental group (50 mg/kg of glibenclamide; n = 5) were studied. During spontaneous breathing at rest, Qpa was 15.0 ml.min-1 x 100 g-1 and decreased by 5% in the presence of glibenclamide. Diaphragmatic pacing (30 min-1) generated by phrenic nerve pacing produced an initial diaphragmatic tension-time index of 0.25 in both groups. A 50% decay in transdiaphragmatic pressure was reached at 165 s in the experimental group compared with 421 s in the control group. Diaphragmatic pacing increased Qpa by 46% in the experimental group and 65% in the control group, yielding a 63% greater vascular resistance in the experimental group. Phrenic vein K+ content at rest was unchanged by the presence of glibenclamide, being 3.6 +/- 0.16 mmol/l compared with 3.5 +/- 0.19 mmol/l in the control group. Phrenic nerve pacing in the control group produced a 13% increase in phrenic vein K+ content, whereas in the experimental group a 16% decrease was observed. We suggest that ATP-sensitive K+ channels play an important role in the modulation of Qpa.
Comtois
A
A
University of Ottawa, Department of Physiology, Ontario, Canada.
Sinderby
C
C
Comtois
N
N
Grassino
A
A
Renaud
J M
JM
D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000758:Anesthesia; D000818:Animals; D002245:Carbon Dioxide / Q000097:blood; D003964:Diaphragm / Q000098:blood supply* / Q000187:drug effects; D004285:Dogs; D005905:Glyburide / Q000494:pharmacology*; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology; D010100:Oxygen / Q000097:blood; D010791:Phrenic Nerve / Q000098:blood supply / Q000502:physiology; D011188:Potassium / Q000378:metabolism; D015221:Potassium Channels / Q000187:drug effects*; D012039:Regional Blood Flow / Q000187:drug effects; D014655:Vascular Resistance / Q000187:drug effects; D014939:Work of Breathing / Q000502:physiology
D015221:Potassium Channels; D002245:Carbon Dioxide; D000255:Adenosine Triphosphate; D011188:Potassium; D010100:Oxygen; D005905:Glyburide