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Hyperpolarization of isolated capillaries from guinea-pig heart induced by $K^{+}$channel openers and glucose deprivation
| Content Provider | Scilit |
|---|---|
| Author | Langheinrich, Ulrike Daut, Jürgen |
| Copyright Year | 1997 |
| Description | Journal: The Journal of physiology 1 The present study was designed to test if microvascular coronary endothelial cells express ATP–sensitive $K^{+}$ channels $(K_{ATP}$ channels). We performed microfluorometric measurements of the membrane potential of freshly isolated guinea‐pig coronary capillaries equilibrated with the voltage–sensitive dye bis‐oxonol (bis‐[1,3–dibutylbarbituric acid] trimethineoxonol, $[DiBAC_{4}$(3)]). 2 The resting membrane potential of capillaries in physiological salt solution was −46±4.2 mV (n= 8) at room temperature (22 °C) as determined after calibration of the fluorescence using the $Na^{+}–K^{+}$ ionophore gramicidin in the presence of different $K^{+}$ concentrations. Spontaneous membrane potential fluctuations of 10–20 mV amplitude were often observed. 3 A reversible, sustained hyperpolarization to a new membrane potential close to the $K^{+}$ equilibrium potential $(E_{K}$) could be induced by application of the $K^{+}$ channel openers HOE 234 (100 nm to 1 μM), diazoxide (10 pm to 100 nM) or pinacidil (100 nM). Subsequent addition of glibenclamide (200 nm to 2 μM) reversed this hyperpolarization. 4 A glibenclamide–sensitive hyperpolarization of coronary capillaries to values near $E_{K}$ was also observed upon omission of D‐glucose (10 mM) from the superfusing solution or by substituting L‐glucose for D‐glucose. Maximum hyperpolarization was reached in less than 10 min. 5 Our results suggest that microvascular coronary endothelial cells express $K_{ATP}$ channels which may be activated during hypoglycaemia. |
| Related Links | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1159558/pdf |
| Ending Page | 408 |
| Page Count | 12 |
| Starting Page | 397 |
| ISSN | 00223751 |
| e-ISSN | 14697793 |
| DOI | 10.1111/j.1469-7793.1997.397bk.x |
| Journal | The Journal of physiology |
| Issue Number | 2 |
| Volume Number | 502 |
| Language | English |
| Publisher | Wiley-Blackwell |
| Publisher Date | 1997-07-01 |
| Access Restriction | Open |
| Subject Keyword | Journal: The Journal of physiology Hyperpolarization |
| Content Type | Text |
| Resource Type | Article |
| Subject | Physiology Sports Science |
