Intracellular Ca2+ regulating proteins in vascular smooth muscle cells are altered with type 1 diabetes due to the direct effects of hyperglycemia

Cardiovascular Diabetology

Original Investigation

Yvonne M Searls¹  Lisa Stehno-Bittel¹  Rajprasad Loganathan¹  Irina V Smirnova¹ 

[1] Department of Physical Therapy and Rehabilitation Science, University of Kansas Medical Center, Kansas City, KS, 66160, USA;

关键词: Sarcoplasmic Reticulum;    Diabetic Animal;    Thapsigargin;    High Glucose Condition;    Nondiabetic Control;   

DOI  :  10.1186/1475-2840-9-8

 received in 2009-07-26, accepted in 2010-02-01,  发布年份 2010

来源: Springer

【 摘 要 】

BackgroundDiminished calcium (Ca2+) transients in response to physiological agonists have been reported in vascular smooth muscle cells (VSMCs) from diabetic animals. However, the mechanism responsible was unclear.Methodology/Principal FindingsVSMCs from autoimmune type 1 Diabetes Resistant Bio-Breeding (DR-BB) rats and streptozotocin-induced rats were examined for levels and distribution of inositol trisphosphate receptors (IP3R) and the SR Ca2+ pumps (SERCA 2 and 3). Generally, a decrease in IP3R levels and dramatic increase in ryanodine receptor (RyR) levels were noted in the aortic samples from diabetic animals. Redistribution of the specific IP3R subtypes was dependent on the rat model. SERCA 2 was redistributed to a peri-nuclear pattern that was more prominent in the DR-BB diabetic rat aorta than the STZ diabetic rat. The free intracellular Ca2+ in freshly dispersed VSMCs from control and diabetic animals was monitored using ratiometric Ca2+ sensitive fluorophores viewed by confocal microscopy. In control VSMCs, basal fluorescence levels were significantly higher in the nucleus relative to the cytoplasm, while in diabetic VSMCs they were essentially the same. Vasopressin induced a predictable increase in free intracellular Ca2+ in the VSMCs from control rats with a prolonged and significantly blunted response in the diabetic VSMCs. A slow rise in free intracellular Ca2+ in response to thapsigargin, a specific blocker of SERCA was seen in the control VSMCs but was significantly delayed and prolonged in cells from diabetic rats. To determine whether the changes were due to the direct effects of hyperglycemica, experiments were repeated using cultured rat aortic smooth muscle cells (A7r5) grown in hyperglycemic and control conditions. In general, they demonstrated the same changes in protein levels and distribution as well as the blunted Ca2+ responses to vasopressin and thapsigargin as noted in the cells from diabetic animals.Conclusions/SignificanceThis work demonstrates that the previously-reported reduced Ca2+ signaling in VSMCs from diabetic animals is related to decreases and/or redistribution in the IP3R Ca2+ channels and SERCA proteins. These changes can be duplicated in culture with high glucose levels.

【 授权许可】

Unknown   
© Searls et al; licensee BioMed Central Ltd. 2010. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.