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Ca2+-pumps and Na2+-Ca2+-exchangers in coronary artery endothelium versus smooth muscle.

Szewczyk MM, Davis KA, Samson SE, Simpson F, Rangachari PK, Grover AK - J. Cell. Mol. Med. (2007 Jan-Feb)

Bottom Line: Vascular endothelial cells (EC) and smooth muscle cells (SMC) require a decrease in cytoplasmic Ca2+ concentration after activation.Since the two cell types differ in their structure and function, we compared the activities of PMCA, NCX and SERCA in pig coronary artery EC and SMC, the types of isoforms expressed using RT-PCR, and their protein abundance using Western blots.PMCA, SERCA and NCX differ in their affinities for Ca2+ and regulation.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, McMaster University, Hamilton, Ontario, Canada.

ABSTRACT
Vascular endothelial cells (EC) and smooth muscle cells (SMC) require a decrease in cytoplasmic Ca2+ concentration after activation. This can be achieved by Ca2+ sequestration by the sarco-/endoplasmic reticulum Ca2+ pumps (SERCA) and Ca2+ extrusion by plasma membrane Ca2+ pumps (PMCA) and Na+-Ca2+-exchangers (NCX). Since the two cell types differ in their structure and function, we compared the activities of PMCA, NCX and SERCA in pig coronary artery EC and SMC, the types of isoforms expressed using RT-PCR, and their protein abundance using Western blots. The activity of NCX is higher in EC than in SMC but those of PMCA and SERCA is lower. Consistently, the protein abundance for NCX protein is higher in EC than in SMC and those of PMCA and SERCA is lower. Based on RT-PCR experiments, the types of RNA present are as follows: EC for PMCA1 while SMC for PMCA4 and PMCA1; EC for SERCA2 and SERCA3 and SMC for SERCA2. Both EC and SMC express NCX1 (mainly NCX1.3). PMCA, SERCA and NCX differ in their affinities for Ca2+ and regulation. Based on these observations and the literature, we conclude that the tightly regulated Ca2+ removal systems in SMC are consistent with the cyclical control of contractility of the filaments and those in EC are consistent with Ca2+ regulation of the endothelial nitric oxide synthase near the cell surface. The differences between EC and SMC should be considered in therapeutic interventions of cardiovascular diseases.

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Related in: MedlinePlus

Comparison of SERCA, PMCA and NCX activities EC and SMC. The relative value for each activity was computed taking the mean value in SMC as 100 %.
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fig06: Comparison of SERCA, PMCA and NCX activities EC and SMC. The relative value for each activity was computed taking the mean value in SMC as 100 %.

Mentions: The activities of SERCA, PMCA and NCX were determined using different preparations and hence the absolute activities of the three transporters should not be compared to each other. Therefore, activities of PMCA, SERCA, and NCX in EC are presented as percent of the corresponding values in SMC in Fig. 6. As shown in Fig. 6, the PMCA activity was lower in EC than in SMC. SERCA activity in EC was also lower than in SMC. In contrast, NCX activity was much higher in EC than in SMC. Thus, activities of the two Ca2+ pumps were lower in EC than in SMC but the NCX activity was greater in EC.


Ca2+-pumps and Na2+-Ca2+-exchangers in coronary artery endothelium versus smooth muscle.

Szewczyk MM, Davis KA, Samson SE, Simpson F, Rangachari PK, Grover AK - J. Cell. Mol. Med. (2007 Jan-Feb)

Comparison of SERCA, PMCA and NCX activities EC and SMC. The relative value for each activity was computed taking the mean value in SMC as 100 %.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4401226&req=5

fig06: Comparison of SERCA, PMCA and NCX activities EC and SMC. The relative value for each activity was computed taking the mean value in SMC as 100 %.
Mentions: The activities of SERCA, PMCA and NCX were determined using different preparations and hence the absolute activities of the three transporters should not be compared to each other. Therefore, activities of PMCA, SERCA, and NCX in EC are presented as percent of the corresponding values in SMC in Fig. 6. As shown in Fig. 6, the PMCA activity was lower in EC than in SMC. SERCA activity in EC was also lower than in SMC. In contrast, NCX activity was much higher in EC than in SMC. Thus, activities of the two Ca2+ pumps were lower in EC than in SMC but the NCX activity was greater in EC.

Bottom Line: Vascular endothelial cells (EC) and smooth muscle cells (SMC) require a decrease in cytoplasmic Ca2+ concentration after activation.Since the two cell types differ in their structure and function, we compared the activities of PMCA, NCX and SERCA in pig coronary artery EC and SMC, the types of isoforms expressed using RT-PCR, and their protein abundance using Western blots.PMCA, SERCA and NCX differ in their affinities for Ca2+ and regulation.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, McMaster University, Hamilton, Ontario, Canada.

ABSTRACT
Vascular endothelial cells (EC) and smooth muscle cells (SMC) require a decrease in cytoplasmic Ca2+ concentration after activation. This can be achieved by Ca2+ sequestration by the sarco-/endoplasmic reticulum Ca2+ pumps (SERCA) and Ca2+ extrusion by plasma membrane Ca2+ pumps (PMCA) and Na+-Ca2+-exchangers (NCX). Since the two cell types differ in their structure and function, we compared the activities of PMCA, NCX and SERCA in pig coronary artery EC and SMC, the types of isoforms expressed using RT-PCR, and their protein abundance using Western blots. The activity of NCX is higher in EC than in SMC but those of PMCA and SERCA is lower. Consistently, the protein abundance for NCX protein is higher in EC than in SMC and those of PMCA and SERCA is lower. Based on RT-PCR experiments, the types of RNA present are as follows: EC for PMCA1 while SMC for PMCA4 and PMCA1; EC for SERCA2 and SERCA3 and SMC for SERCA2. Both EC and SMC express NCX1 (mainly NCX1.3). PMCA, SERCA and NCX differ in their affinities for Ca2+ and regulation. Based on these observations and the literature, we conclude that the tightly regulated Ca2+ removal systems in SMC are consistent with the cyclical control of contractility of the filaments and those in EC are consistent with Ca2+ regulation of the endothelial nitric oxide synthase near the cell surface. The differences between EC and SMC should be considered in therapeutic interventions of cardiovascular diseases.

Show MeSH
Related in: MedlinePlus