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Graded response of K+ current, membrane potential, and [Ca2+]i to hypoxia in pulmonary arterial smooth muscle.
| Content Provider | Semantic Scholar |
|---|---|
| Author | Olschewski, Andrea Zhigang Nelson, Daniel P. Weir, Edward Kenneth |
| Copyright Year | 2002 |
| Abstract | Many studies indicate that hypoxic inhibition of some K+ channels in the membrane of the pulmonary arterial smooth muscle cells (PASMCs) plays a part in initiating hypoxic pulmonary vasoconstriction. The sensitivity of the K+ current (I(k)), resting membrane potential (E(m)), and intracellular Ca2+ concentration ([Ca2+]i) of PASMCs to different levels of hypoxia in these cells has not been explored fully. Reducing PO2 levels gradually inhibited steady-state I(k) of rat resistance PASMCs and depolarized the cell membrane. The block of I(k) by hypoxia was voltage dependent in that low O2 tensions (3 and 0% O2) inhibited I(k) more at 0 and -20 mV than at 50 mV. As expected, the hypoxia-sensitive I(k) was also 4-aminopyridine sensitive. Fura 2-loaded PASMCs showed a graded increase in [Ca2+]i as PO2 levels declined. This increase was reduced markedly by nifedipine and removal of extracellular Ca2+. We conclude that, as in the carotid body type I cells, PC-12 pheochromocytoma cells, and cortical neurons, increasing severity of hypoxia causes a proportional decrease in I(k) and E(m) and an increase of [Ca2+]i. |
| Starting Page | 925 |
| Ending Page | 925 |
| Page Count | 1 |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://ajplung.physiology.org/content/ajplung/283/5/L1143.full.pdf |
| PubMed reference number | 12376369v1 |
| Volume Number | 283 |
| Issue Number | 5 |
| Journal | American journal of physiology. Lung cellular and molecular physiology |
| Language | English |
| Access Restriction | Open |
| Subject Keyword | Carotid Body Fura-2 Hypoxia Membrane Potentials Muscle Cells Myocytes, Smooth Muscle Nifedipine Oxygen PC 12 ester PO-2 Pheochromocytoma Plasma membrane Potassium Rest Smooth muscle (tissue) Somatotype Tension Tissue membrane Vascular constriction (function) dalfampridine |
| Content Type | Text |
| Resource Type | Article |
