The Journal of Neurophysiology Vol. 77 No. 1 January 1997, pp. 386-392
Copyright ©1997 The American Physiological Society

Mediation by Intracellular Calcium-Dependent Signals of Hypoxic Hyperpolarization in Rat Hippocampal CA1 Neurons In Vitro

S. Yamamoto, E. Tanaka, and H. Higashi

Department of Physiology, Kurume University School of Medicine, Kurume 830, Japan

Yamamoto, S., E. Tanaka and H. Higashi. Mediation by intracellular calcium-dependent signals of hypoxic hyperpolarization in rat hippocampal CA1 neurons in vitro. J. Neurophysiol. 77: 386-392, 1997. In response to oxygen deprivation, CA1 pyramidal neurons show a hyperpolarization (hypoxic hyperpolarization), which is associated with a reduction in neuronal input resistance. The role of extra- and intracellular Ca²⁺ ions in hypoxic hyperpolarization was investigated. The hypoxic hyperpolarization was significantly depressed by tolbutamide (100 µM); moreover, the response was reversed in its polarity in medium containing tolbutamide (100 µM), low Ca²⁺ (0.25 mM), and Co²⁺ (2 mM), suggesting that the hypoxic hyperpolarization is mediated by activation of both ATP-sensitive K⁺ (K_ATP) channels and Ca²⁺-dependent K⁺ channels. The hypoxic depolarization in medium containing tolbutamide, low Ca²⁺, and Co²⁺ is probably due to inhibition of the electrogenic Na⁺-K⁺ pump and concomitant accumulation of interstitial K⁺. Hypoxic hyperpolarizations were depressed in either low Ca²⁺ (0.25 or 1.25 mM) or high Ca²⁺ (5 or 7.5 mM) medium (control: 2.5 mM), indicating that there is an optimal extracellular Ca²⁺ concentration required to producethe hypoxic hyperpolarization. Bis-(o-aminophenoxy)-N,N,N,Ntetraacetic acid (BAPTA)-AM (50-100 µM), procaine (300 µM), or ryanodine (10 µM) significantly depressed the hypoxic hyperpolarization, suggesting that Ca²⁺ released from intracellular Ca²⁺ stores may have an important role in the generation of hypoxic hyperpolarization. The high-affinity calmodulin inhibitor N-(6-amino-hexyl)-5-chloro-1-naphthalenesulfonomide hydrochloride (W-7) (5 µM) completely blocked, whereas the low-affinity calmodulin inhibitor N-(6-aminohexyl)-1-naphthalenesulfonomide hydrochloride (W-5) (50 µM) did not affect, the hypoxic hyperpolarization. The calmodulin inhibitor trifluoperazine (50 µM) also suppressed the hypoxic hyperpolarization. In addition, calcium/calmodulin kinase II inhibitor 1-[N,O-bis(1,5-isoquinol-inesulfonyl)-N-methyl-L-tyrosyl]-4-phenyl-piperazine (KN-62) (10 µM) markedly depressed the amplitude and net outward current of the hypoxic hyperpolarization without affecting the reversal potential. In contrast, neither the myosin light chain kinase inhibitor 1-(5-iodonaphthalene-1-sulfonyl)-1H-hexa-hydro-1,4-diazepin hydrochloride (ML-7) (10 µM) nor the protein kinase A inhibitorN-[2-(p-bromocinnamyl-amino)ethyl]-5-isoquinolinesulfonamide(H-89) (1 µM) significantly altered the hypoxic hyperpolarization. These results suggest that calmodulin kinase II, which is activated by calmodulin, may contribute to the generation of the hypoxic hyperpolarization. In conclusion, the present study indicates that, in the majority of hippocampal CA1 neurons, the hypoxic hyperpolarization is due to activation of both K_ATP channels and Ca²⁺-dependent K⁺ channels.

This article has been cited by other articles:

				T. Kawano, V. Zoga, G. Gemes, J. B. McCallum, H.-E. Wu, D. Pravdic, M.-Y. Liang, W.-M. Kwok, Q. Hogan, and C. Sarantopoulos Suppressed Ca2+/CaM/CaMKII-dependent KATP channel activity in primary afferent neurons mediates hyperalgesia after axotomy PNAS, May 26, 2009; 106(21): 8725 - 8730. [Abstract] [Full Text] [PDF]

				D. D'Agostino, E. Mazza Jr., and J. A. Neubauer Heme oxygenase is necessary for the excitatory response of cultured neonatal rat rostral ventrolateral medulla neurons to hypoxia Am J Physiol Regulatory Integrative Comp Physiol, January 1, 2009; 296(1): R102 - R118. [Abstract] [Full Text] [PDF]

				H.-S. Sun, Z.-P. Feng, T. Miki, S. Seino, and R. J. French Enhanced Neuronal Damage After Ischemic Insults in Mice Lacking Kir6.2-Containing ATP-Sensitive K+ Channels J Neurophysiol, April 1, 2006; 95(4): 2590 - 2601. [Abstract] [Full Text] [PDF]

				H. Misonou, D. P. Mohapatra, M. Menegola, and J. S. Trimmer Calcium- and Metabolic State-Dependent Modulation of the Voltage-Dependent Kv2.1 Channel Regulates Neuronal Excitability in Response to Ischemia J. Neurosci., November 30, 2005; 25(48): 11184 - 11193. [Abstract] [Full Text] [PDF]

				N. J. Allen, D. J. Rossi, and D. Attwell Sequential Release of GABA by Exocytosis and Reversed Uptake Leads to Neuronal Swelling in Simulated Ischemia of Hippocampal Slices J. Neurosci., April 14, 2004; 24(15): 3837 - 3849. [Abstract] [Full Text] [PDF]

				K. Yamada and N. Inagaki ATP-Sensitive K+ Channels in the Brain: Sensors of Hypoxic Conditions Physiology, June 1, 2002; 17(3): 127 - 130. [Abstract] [Full Text] [PDF]

				V. Dzhala, I. Khalilov, Y. Ben-Ari, and R. Khazipov Neuronal mechanisms of the anoxia-induced network oscillations in the rat hippocampus in vitro J. Physiol., October 15, 2001; 536(2): 521 - 531. [Abstract] [Full Text] [PDF]

				X. X. Chi and Z. C. Xu Differential Changes of Potassium Currents in CA1 Pyramidal Neurons After Transient Forebrain Ischemia J Neurophysiol, December 1, 2000; 84(6): 2834 - 2843. [Abstract] [Full Text] [PDF]

				M. R. Pelletier, P. A. Pahapill, P. S. Pennefather, and P. L. Carlen Analysis of Single KATP Channels in Mammalian Dentate Gyrus Granule Cells J Neurophysiol, November 1, 2000; 84(5): 2291 - 2301. [Abstract] [Full Text] [PDF]

				B Lancaster and A M Batchelor Novel action of BAPTA series chelators on intrinsic K+ currents in rat hippocampal neurones J. Physiol., January 15, 2000; 522(2): 231 - 246. [Abstract] [Full Text] [PDF]

				M. Tanabe, M. Mori, B. H. Gahwiler, and U. Gerber Apamin-Sensitive Conductance Mediates the K+ Current Response During Chemical Ischemia in CA3 Pyramidal Cells J Neurophysiol, December 1, 1999; 82(6): 2876 - 2882. [Abstract] [Full Text] [PDF]

				M. Zhu, C. H. Gelband, P. Posner, and C. Sumners Angiotensin II Decreases Neuronal Delayed Rectifier Potassium Current: Role of Calcium/Calmodulin-Dependent Protein Kinase II J Neurophysiol, September 1, 1999; 82(3): 1560 - 1568. [Abstract] [Full Text] [PDF]

				T. Isagai, N. Fujimura, E. Tanaka, S. Yamamoto, and H. Higashi Membrane Dysfunction Induced by In Vitro Ischemia in Immature Rat Hippocampal CA1 Neurons J Neurophysiol, April 1, 1999; 81(4): 1866 - 1871. [Abstract] [Full Text] [PDF]

				H. Le Corronc, B. Hue, and R. M. Pitman Ionic Mechanisms Underlying Depolarizing Responses of an Identified Insect Motor Neuron to Short Periods of Hypoxia J Neurophysiol, January 1, 1999; 81(1): 307 - 318. [Abstract] [Full Text] [PDF]

				G. Erdemli, Y. Z. Xu, and K. Krnjevic Potassium Conductance Causing Hyperpolarization of CA1 Hippocampal Neurons During Hypoxia J Neurophysiol, November 1, 1998; 80(5): 2378 - 2390. [Abstract] [Full Text] [PDF]

				E. Guatteo, M. Federici, A. Siniscalchi, T. Knopfel, N. B. Mercuri, and G. Bernardi Whole Cell Patch-Clamp Recordings of Rat Midbrain Dopaminergic Neurons Isolate a Sulphonylurea- and ATP-Sensitive Component of Potassium Currents Activated by Hypoxia J Neurophysiol, March 1, 1998; 79(3): 1239 - 1245. [Abstract] [Full Text] [PDF]

				E. Tanaka, S. Yamamoto, Y. Kudo, S. Mihara, and H. Higashi Mechanisms Underlying the Rapid Depolarization Produced by Deprivation of Oxygen and Glucose in Rat Hippocampal CA1 Neurons In Vitro J Neurophysiol, August 1, 1997; 78(2): 891 - 902. [Abstract] [Full Text] [PDF]

				N. Fujimura, E. Tanaka, S. Yamamoto, M. Shigemori, and H. Higashi Contribution of ATP-Sensitive Potassium Channels to Hypoxic Hyperpolarization in Rat Hippocampal CA1 Neurons In Vitro J Neurophysiol, January 1, 1997; 77(1): 378 - 385. [Abstract] [Full Text] [PDF]