Fluorescent Ligand Binding in α1-adrenoceptor Knockout Mice Demonstrates that all Three α1-adrenoceptor Subtypes Exist in Smooth Muscle Cells in the Mouse Carotid Artery

Methven, L., Daly, C. and McGrath, I. (2007) Fluorescent Ligand Binding in α1-adrenoceptor Knockout Mice Demonstrates that all Three α1-adrenoceptor Subtypes Exist in Smooth Muscle Cells in the Mouse Carotid Artery. Life Sciences 2007, 2007.

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Publisher's URL: https://www.physoc.org/abstracts/fluorescent-ligand-binding-in-1-adrenoceptor-knockout-mice-demonstrates-that-all-three-1-adrenoceptor-subtypes-exist-in-smooth-muscle-cells-in-the-mouse-carotid-artery/

Abstract

The distribution of α1-adrenoceptors (α1-ARs) in smooth muscle cells (SMCs) of the carotid artery was examined using QAPB, a fluorescent ligand for α1-ARs, in the wild type (WT) and α1-AR knockout (KO) mice. Methods Fresh carotids were incubated in 100nM QAPB/PSS solution (21°C, 120 minutes). α1B/D-KO arteries were also co-incubated with 100nM QAPB/100nM RS100329 (α1A-AR selective antagonist). Arteries were sliced open and laid flat on a microscope slide (Miquel RM et al., 2005). All arteries were visualised using the Bio-Rad Radiance 2100 Confocal Laser Scanning System. An excitation/emission of 488nm/515nm was used with a X40 oil immersion objective (NA 0.75). Integrated intensity was obtained from region statistics. The number of pixels at each intensity was obtained and used to calculate the total fluorescence at each intensity level. Mean data was displayed in histogram plots to quantify the observations made by eye. Results QAPB binding was evenly distributed throughout the WT carotid, in which SMCs were clearly defined. In the α1B-KO, SMCs were clearly defined by QAPB and evenly distributed. In both the α1B/D-KO and α1D-KO QAPB binding was markedly reduced and varied between individual cells. The leftward displacement of the histograms and the decrease in total intensity (Table 1) demonstrated that fluorescence was reduced for all three KO compared to the WT. RS100 329 abolished QAPB binding (total intensity 2.35E+6± 6.3E+5). Conclusions The reduced intensity in the α1B-KO suggests that the total a1-AR population was reduced and that the α1B-AR is present in the WT. In the α1D-KO fluorescence was reduced more than in the α1B-KO, consistent with a major α1D-AR population in the WT. Furthermore, the presence of QAPB binding in the α1B/D-KO, which was abolished by RS100 329, highlights that an α1A-AR population may be present in the WT. In conclusion, the total α1-AR population is decreased in the KOs and suggests that all three α1-AR subtypes exist in SMCs in the WT carotid artery.

Item Type:Conference or Workshop Item
Additional Information:Poster Communication.
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Daly, Professor Craig and McGrath, Miss Isla and Methven, Dr Laura
Authors: Methven, L., Daly, C., and McGrath, I.
College/School:College of Medical Veterinary and Life Sciences > School of Life Sciences

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