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Glutamate regulates local and global Ca 2+ signals in myocytes of piglet brain slice arterioles through astrocyte‐ and heme oxygenase‐dependent mechanisms
Author(s) -
Zhao Guiling,
Xi Qi,
Umstot Edward,
Leffler Charles W,
Jaggar Jonathan H
Publication year - 2009
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.23.1_supplement.613.14
Subject(s) - glutamate receptor , heme oxygenase , astrocyte , chemistry , arteriole , heme , excitatory postsynaptic potential , neuroscience , biophysics , biology , biochemistry , endocrinology , central nervous system , receptor , circulatory system , enzyme
Glutamate is the principal cerebral excitatory neurotransmitter and dilates cerebral arterioles to match blood flow to neural activity. Arterial contractility is regulated by local and global Ca 2+ signals that occur in myocytes, but modulation of these signals by glutamate is poorly understood. Using high‐speed confocal imaging we measured glutamate regulation of Ca 2+ signals that occur in myocytes within arterioles of piglet tangential brain slices. Glutamate elevated Ca 2+ spark frequency ~188% and reduced global intracellular Ca 2+ concentration ([Ca 2+ ] i ) to ~76% of control, but did not alter Ca 2+ waves. Cerebral arteriole isolation from brain slices abolished glutamate‐induced Ca 2+ signal modulation. In slices treated with L‐AAA, a glial toxin, glutamate did not alter Ca 2+ sparks or global [Ca 2+ ] i , but activated Ca 2+ waves. This shift in Ca 2+ signal modulation by glutamate did not occur in slices treated with D‐AAA, an inactive isomer of L‐AAA. In the presence of CrMP, a heme oxygenase blocker, glutamate inhibited Ca 2+ sparks and Ca 2+ waves and did not alter global [Ca 2+ ] i . Collectively, these data indicate that glutamate can modulate local and global Ca 2+ signals in arteriole myocytes via mechanisms that require astrocytes and heme‐oxygenase. In the absence of astrocytes or functional heme oxygenase, effects of glutamate on arterial Ca 2+ signals were absent or the opposite of those in the intact system.