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Reduced role of large conductance K Ca channels in the response to noradrenaline after ischemia‐reperfusion in goat cerebral arteries
Author(s) -
GarciaVillalon Angel Luis,
Carreño Gonzalo,
Fernandez Nuria,
Monge Luis,
Dieguez Godofredo
Publication year - 2011
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.25.1_supplement.1024.17
Subject(s) - iberiotoxin , apamin , ischemia , cerebral arteries , calcium activated potassium channel , medicine , conductance , anesthesia , cardiology , constriction , potassium channel , chemistry , endocrinology , mathematics , combinatorics
Vascular calcium‐activated potassium (K Ca ) channels seem to play a role in the regulation of cerebral blood flow. To analyze their functional state after cerebral ischemia‐reperfusion, the left middle cerebral artery (MCA) of anesthetized goats was subjected to 120‐min occlusion followed by 60‐min reperfusion. Isolated segments from the left (ischemic) and right (control) MCA exhibited constriction to noradrenaline (10 −8 ‐10 −4 M, in the presence of β‐adrenoceptor blockade) that was greater in ischemic arteries. The large‐conductance K Ca channel inhibitor Iberiotoxin (10 −7 M) enhanced the contraction to noradrenaline in both control and ischemic arteries, but this effect was significantly lower in ischemic (21±12 %) than in control vessels (72±18 %, p<0.05). TRAM‐34 (2×10 −8 M, intermediate‐conductance K Ca channel inhibitor) or Apamin (10 −6 M, small‐conductance K Ca channel inhibitor) did not modify the noradrenaline effect in both types of arteries. The NO synthesis inhibitor L‐NAME (10 −4 M) potentiated the response to noradrenaline similarly in control and ischemic arteries. These results suggest that the response to noradrenaline is enhanced after ischemia‐reperfusion due, in part, to impaired activation of large‐conductance K Ca channels. NO might not be accounting for the adrenergic activation of K channels. (Supported by Ministerio de Ciencia e Innovación grant Nº SAF2008‐01410).