Protein kinase C-epsilon-null mice have decreased hypoxic pulmonary vasoconstriction.
PKC contributes to regulation of pulmonary vascular reactivity in response to hypoxia. The role of individual PKC isozymes is less clear. We used a knockout (null, -/-) mouse to test the hypothesis that PKC-epsilon is important in acute hypoxic pulmonary vasoconstriction (HPV). We asked whether deletion of PKC-epsilon would decrease acute HPV in adult C57BL6xSV129 mice. In isolated, salt solution-perfused lung, reactivity to acute hypoxic challenges (0% and 3% O(2)) was compared with responses to angiotensin II (ANG II) and KCl. PKC-epsilon -/- mice had decreased HPV, whereas responses to ANG II and KCl were preserved. Inhibition of nitric oxide synthase (NOS) with nitro-l-arginine augmented HPV in PKC-epsilon +/+ but not -/- mice. Inhibition of Ca(2+)-gated K(+) channels (K(Ca)) with charybdotoxin and apamin did not enhance HPV in -/- mice relative to wild-type (+/+) controls. In contrast, the voltage-gated K(+) channel (K(V)) antagonist 4-aminopyridine increased the response of -/- mice beyond that of +/+ mice. This suggested that increased K(V) channel expression could contribute to blunted HPV in PKC-epsilon -/- mice. Therefore, expression of the O(2)-sensitive K(V) channel subunit Kv3.1b (100-kDa glycosylated form and 70-kDa core protein) was compared in whole lung and pulmonary artery smooth muscle cell (PASMC) lysates from +/+ and -/- mice. A subtle increase in Kv3.1b was detected in -/- vs. +/+ whole lung lysates. A much greater rise in Kv3.1b expression was found in -/- vs. +/+ PASMC. Thus deletion of PKC-epsilon blunts murine HPV. The decreased response could not be attributed to a general loss in vasoreactivity or derangements in NOS or K(Ca) channel activity. Instead, the absence of PKC-epsilon allows increased expression of K(V) channels (like Kv3.1b) to occur in PASMC, which likely contributes to decreased HPV.
Littler
Cassana M
CM
Cardiovascular Pulmonary Research Laboratory, University of Colorado Health Sciences Center, Denver, Colorado 80262, USA.
Morris
Kenneth G
KG
Fagan
Karen A
KA
McMurtry
Ivan F
IF
Messing
Robert O
RO
Dempsey
Edward C
EC
D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D017353:Gene Deletion; D000860:Hypoxia / Q000503:physiopathology*; D008168:Lung / Q000098:blood supply* / Q000737:chemistry; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009131:Muscle, Smooth, Vascular / Q000737:chemistry; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D010100:Oxygen / Q000008:administration & dosage / Q000494:pharmacology; D026902:Potassium Channel Blockers / Q000494:pharmacology; D015221:Potassium Channels / Q000032:analysis / Q000187:drug effects / Q000502:physiology; D024642:Potassium Channels, Voltage-Gated; D011189:Potassium Chloride / Q000494:pharmacology; D011493:Protein Kinase C / Q000172:deficiency* / Q000235:genetics / Q000502:physiology; D051744:Protein Kinase C-epsilon; D011651:Pulmonary Artery / Q000737:chemistry / Q000503:physiopathology; D051670:Shaw Potassium Channels; D014661:Vasoconstriction
D004791:Enzyme Inhibitors; C490839:Kcnc1 protein, mouse; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D051670:Shaw Potassium Channels; D000804:Angiotensin II; D011189:Potassium Chloride; D019001:Nitric Oxide Synthase; C497256:Prkce protein, mouse; D011493:Protein Kinase C; D051744:Protein Kinase C-epsilon; D010100:Oxygen; D002118:Calcium