Premium
Rate constants suggest three mechanisms for porcine pulmonary arterial (PPA) contraction
Author(s) -
Badenhop Sarah B,
Desormeaux Victoria,
Kumar Aswin,
Conover Sam,
Fawley Nick,
Ha Soo,
Hess Lauren,
Pelaez Nancy
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.1061.3
Subject(s) - contraction (grammar) , chemistry , calcium , extracellular , ryanodine receptor , tetrandrine , biophysics , egta , calcium in biology , intracellular , biochemistry , endocrinology , biology , pharmacology , organic chemistry
Vascular Smooth Muscle (VSM) uses both extracellular calcium ([Ca 2+ ] o ) and intracellular stores of calcium to signal a typical contraction. In contrast we find that fourth generation porcine pulmonary artery (PPA) contracts after high potassium depolarization with and without the presence of [Ca 2+ ] o . The contractile behavior of PPA was modeled using JSIM Physiome Modeling software. PPA contraction in the presence of [Ca 2+ ] o was characterized by both a fast and slow rate constant, whereas only a slow rate constant was observed without the presence of [Ca 2+ ] o . Only this slow rate constant was detected in the presence of various calcium influx inhibitors including tetrandrine, caffeine and ethylene glycol tetraacetic acid (EGTA). High potassium‐induced contraction of PPA, with either the absence of [Ca 2+ ] o or the inhibition of Ca 2+ entry via voltage gated Ca 2+ channels (VOCCs), suggests either the use of intracellular stores of Ca 2+ through a novel signal transduction pathway or an unknown Ca 2+ independent mechanism for contraction. PPA also contracted using H 2 O 2 , but with contractile rate that differed from those previously observed. The rates calculated from 3 mM H 2 O 2 contractions were intermediate, but did not fit the exponential curve for the fast and slow rate constants. The intermediate curve was also dependent on [H 2 O 2 ]. The intermediate rate constants suggest an alternative third mechanism underlying PPA contraction in response to H 2 O 2 .