Imaging evidence for endothelin ETA/ETB receptor heterodimers in isolated rat mesenteric resistance arteries

Dimitrios Kapsokalyvas, Paul M. H. Schiffers, Nathan Maij, Dennis P. Suylen, Tilman M. Hackeng, Marc A. M. J. van Zandvoort, Jo G. R. De Mey*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

7 Citations (Web of Science)


Aims: In engineered cells, endothelin ETA and ETB receptors can heterodimerize. We tested whether this can also be observed in native tissue. Main methods: Rat mesenteric resistance arteries (rMRA) were maintained in organ culture for 24 h to upregulate ETB-mediated contractions in addition to their normal ETA-mediated responses. They were then exposed to 100 nM linear ET-1 (ETB-agonist) labeled with Oregon Green 488 (OG488/L.-ET-1) and/or to 16 nM intact ET-1 (ETA/ETB-agonist) labeled with the rhodamine dye TAMRA (TAMRA/ET-1). Two photon laser scanning microscopy (TPLSM) was used for the visualization of their binding in the tissue. Fluorescence Lifetime Imaging Microscopy (FLIM) was employed for measurements of the OG488/L-ET-1 lifetime in the absence and presence of TAMRA/ET-1. Key findings: After incubation with the labeled ligands, medial smooth muscle cells (SMCs) were efficiently stained and became visible under TPLSM. TAMRA/ET-1 bound to all SMCs whereas OG488/L-ET-1 stained only groups of SMCs. Interaction of the two receptor subtypes in SMC was investigated in double staining experiments. Fluorescence lifetime of OG488/L.-ET-1 was reduced in the presence of TAMRA/ET-1, which indicates the occurrence of Fluorescence Resonant Energy Transfer (FRET) and suggests close proximity of the two receptor subtypes within the arterial wall. Significance: The methodology that is introduced by these new observations may be useful to assess ET-receptor heterodimerization in biopsies from relevant experimental animal models and human patients.
Original languageEnglish
Pages (from-to)36-41
JournalLife Sciences
Issue number1-2
Publication statusPublished - 28 Aug 2014


  • Endothelin
  • Endothelin receptors
  • Resistance arteries
  • FLIM
  • FRET
  • Two photon microscopy

Cite this