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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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SERCA activity in EC and SMC. A. 45Ca2+ uptake by permeabilized EC or SMC from solutions containing 0 or 2 μM thapsigargin. B. SERCA-dependent 45Ca2+ uptake in EC and SMC defined as difference between the uptake in the absence and presence of thapsigargin determined from A.
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fig03: SERCA activity in EC and SMC. A. 45Ca2+ uptake by permeabilized EC or SMC from solutions containing 0 or 2 μM thapsigargin. B. SERCA-dependent 45Ca2+ uptake in EC and SMC defined as difference between the uptake in the absence and presence of thapsigargin determined from A.

Mentions: Time course of the 45Ca2+ uptake by permeabilized EC and SMC with and without thapsigargin is shown in Fig. 3A. In the presence of thapsigargin, both EC and SMC showed only small 45Ca2+ uptake but the uptake was much greater in the absence of thapsigargin.The thap-sigargin-sensitive component of the uptake is shown in Fig. 3B. The SERCA activity in EC (0.15 ±0.05 nmol/min/mg protein) was also lower than in SMC (1.5 ±0.3 nmol/min/mg protein). Thus, the SERCA activity in EC was only 10 ±3% of that in SMC.


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)

SERCA activity in EC and SMC. A. 45Ca2+ uptake by permeabilized EC or SMC from solutions containing 0 or 2 μM thapsigargin. B. SERCA-dependent 45Ca2+ uptake in EC and SMC defined as difference between the uptake in the absence and presence of thapsigargin determined from A.
© Copyright Policy
Related In: Results  -  Collection

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

fig03: SERCA activity in EC and SMC. A. 45Ca2+ uptake by permeabilized EC or SMC from solutions containing 0 or 2 μM thapsigargin. B. SERCA-dependent 45Ca2+ uptake in EC and SMC defined as difference between the uptake in the absence and presence of thapsigargin determined from A.
Mentions: Time course of the 45Ca2+ uptake by permeabilized EC and SMC with and without thapsigargin is shown in Fig. 3A. In the presence of thapsigargin, both EC and SMC showed only small 45Ca2+ uptake but the uptake was much greater in the absence of thapsigargin.The thap-sigargin-sensitive component of the uptake is shown in Fig. 3B. The SERCA activity in EC (0.15 ±0.05 nmol/min/mg protein) was also lower than in SMC (1.5 ±0.3 nmol/min/mg protein). Thus, the SERCA activity in EC was only 10 ±3% of that in SMC.

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