Calcium-activated K+ channels in cerebral arterioles in piglets are resistant to ischemia

F. Bari, T. M. Louis, D. W. Busija

Research output: Contribution to journalArticle

20 Citations (Scopus)

Abstract

Our previous studies indicate that function of ATP-dependent K+ channels (K(ATP)) in cerebral arterioles is suppressed after ischemia. In the current study, we examined pial arteriolar responses to forskolin, dibutyryl- cAMP, NS-1619, and methionine (met)-enkephalin, activators of calcium- dependent K+ channels (K(Ca)) before and 1 hour after 10 minutes of total, global ischemia in anesthetized piglets. Arteriolar diameters were measured using a closed cranial window and intravital microscopy. All pharmacologic agents were given topically. Baseline diameters were approximately 100 μm, and diameters had returned to normal by i hour after ischemia. Forskolin dilated arterioles by 9 ± 3%, 18 ± 4%, and 31 ± 12% at 5 x 10-8, 5 x 10-7, and 10-6 mol/L, respectively (P <0.05, n = 10). In addition, dibutyryl-cAMP dilated arterioles by 8 ± 2% at 10-4 mol/L and 14 ± 2% at 3 x 10-4 mol/L (P <0.05, n = 6). Also, NS-1619 increased diameter of arterioles by 9 ± 2% at 10-7 mol/L and 17 ± 9% at 10-5 mol/L (P <0.05, n = 5). Finally, met-enkephalin dilated arterioles by 9 ± 2% at 10-8 mol/L and 16 ± 3% at 10-6 mol/L (P <0.05, n = 5). At 1 hour after ischemia, arteriolar dilator effects to forskolin, dibutyryl-cAMP and NS-1619, and met- enkephalin were intact. Thus, in contrast to K(ATP), K(Ca) in cerebral arterioles are resistant to ischemic stress.

Original languageEnglish
Pages (from-to)1152-1156
Number of pages5
JournalJournal of Cerebral Blood Flow and Metabolism
Volume17
Issue number11
Publication statusPublished - 1997

Fingerprint

Calcium-Activated Potassium Channels
Arterioles
Ischemia
Methionine Enkephalin
Colforsin
Adenosine Triphosphate
Calcium
NS 1619

Keywords

  • Cerebral circulation
  • Dibutyryl- cAMP
  • Forskolin
  • Methionine-enkephalin
  • Potassium channels

ASJC Scopus subject areas

  • Endocrinology
  • Neuroscience(all)
  • Endocrinology, Diabetes and Metabolism

Cite this

Calcium-activated K+ channels in cerebral arterioles in piglets are resistant to ischemia. / Bari, F.; Louis, T. M.; Busija, D. W.

In: Journal of Cerebral Blood Flow and Metabolism, Vol. 17, No. 11, 1997, p. 1152-1156.

Research output: Contribution to journalArticle

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AB - Our previous studies indicate that function of ATP-dependent K+ channels (K(ATP)) in cerebral arterioles is suppressed after ischemia. In the current study, we examined pial arteriolar responses to forskolin, dibutyryl- cAMP, NS-1619, and methionine (met)-enkephalin, activators of calcium- dependent K+ channels (K(Ca)) before and 1 hour after 10 minutes of total, global ischemia in anesthetized piglets. Arteriolar diameters were measured using a closed cranial window and intravital microscopy. All pharmacologic agents were given topically. Baseline diameters were approximately 100 μm, and diameters had returned to normal by i hour after ischemia. Forskolin dilated arterioles by 9 ± 3%, 18 ± 4%, and 31 ± 12% at 5 x 10-8, 5 x 10-7, and 10-6 mol/L, respectively (P <0.05, n = 10). In addition, dibutyryl-cAMP dilated arterioles by 8 ± 2% at 10-4 mol/L and 14 ± 2% at 3 x 10-4 mol/L (P <0.05, n = 6). Also, NS-1619 increased diameter of arterioles by 9 ± 2% at 10-7 mol/L and 17 ± 9% at 10-5 mol/L (P <0.05, n = 5). Finally, met-enkephalin dilated arterioles by 9 ± 2% at 10-8 mol/L and 16 ± 3% at 10-6 mol/L (P <0.05, n = 5). At 1 hour after ischemia, arteriolar dilator effects to forskolin, dibutyryl-cAMP and NS-1619, and met- enkephalin were intact. Thus, in contrast to K(ATP), K(Ca) in cerebral arterioles are resistant to ischemic stress.

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