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Intracellular calcium stores contribute to the myogenic response of rat cerebral arteries
Author(s) -
Tam Raymond,
Kerr Paul M,
Plane Frances
Publication year - 2010
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.24.1_supplement.985.19
Subject(s) - cerebral arteries , myograph , myogenic contraction , nicardipine , calcium channel blocker , calcium in biology , medicine , ryanodine receptor , blood pressure , endocrinology , chemistry , calcium , anatomy , vasodilation , smooth muscle
Cerebral blood flow is controlled by autoregulatory mechanisms which maintain blood flow within narrow limits despite large changes in blood pressure. Increases in blood pressure cause small cerebral arteries to constrict, a mechanism called the myogenic response. We investigated the contribution of intracellular calcium stores to the development of myogenic tone in rat middle cerebral arteries. Cerebral arteries mounted in a pressure myograph were subjected to stepwise increases in intra‐vascular pressure (20–120 mmHg), and changes in vessel diameter were recorded in the presence or absence of drugs. Cyclopiazonic (CPA; 10 μM), an inhibitor of the SR Ca 2+ ‐ATPase, attenuated myogenic tone at 80mmHg by 64.2 ± 7.2% (n=5). Caffeine (10 mM), a ryanodine channel opener, reduced myogenic tone by 80.3 ± 6.7% (n=5). The effect of caffeine was not inhibited by iberiotoxin (IBTX 100nM; n=4), a large conductance calcium‐activated potassium channel (BK Ca ) blocker, suggesting that activation of BK Ca is unlikely. When CPA was added in combination with nifedipine (10 μM), an L‐type calcium channel blocker, development of myogenic tone was abolished. In conclusion, our data suggests that release of intracellular calcium from the SR plays an important role in the development of myogenic tone in rat middle cerebral arteries. Funded by Heart and Stroke Foundation and University of Alberta Queen Elizabeth II Award.