This study explores the hypothesis that intracerebral hemorrhage (ICH) promotes release of diffusible factors that can significantly influence the structure and function of cerebral arteries remote from the site of injury, through action on platelet-derived growth factor (PDGF) receptors. Four groups of adult male Sprague Dawley rats were studied (n=8 each): 1) Sham; 2) Sham + 60 mg/kg IP imatinib; 3) ICH (collagenase method); and 4) ICH + 60 mg/kg IP imatinib given 60 min after injury. At 24 hours post-injury, sham artery passive diameters (+3 mM EGTA) averaged 244±7 µm (@60 mmHg). ICH significantly increased passive diameters up to 6.4% and decreased compliance up to 42.5%. For both pressure- and potassium-induced contractions, ICH decreased calcium mobilization up to 26.2% and increased myofilament calcium sensitivity up to 48.4%. ICH reduced confocal colocalization of Smooth Muscle α-Actin (SMαA) with Non-Muscle Myosin Heavy Chain (MHC) and increased its colocalization with Smooth Muscle MHC, suggesting that ICH promoted contractile differentiation. ICH also enhanced colocalization of MLCK with both SMαA and regulatory 20 kDa Myosin Light Chain. All effects of ICH on passive diameter, compliance, contractility, and contractile protein colocalization were significantly reduced or absent in arteries from animals treated with imatinib. These findings support the hypothesis that ICH promotes release into the CSF of vasoactive factors that can diffuse to and promote activation of cerebrovascular PDGF receptors, thereby altering the structure, contractile protein organization, contractility and smooth muscle phenotype of cerebral arteries remote from the site of hemorrhage.
- Cerebral Arteries
- Copyright © 2016, American Journal of Physiology-Regulatory, Integrative and Comparative Physiology