Abstract
Previous work has shown that the genes encoding each α1-adrenoceptor subtype are coexpressed throughout the peripheral vascular system. We have evaluated subtype-selective antibodies as tools to determine the extent of protein expression in arteries. The α1A-, α1B-, and α1D-adrenoceptors were detected in the medial layer of the aorta, caudal, femoral, iliac, renal, superior mesenteric, and mesenteric resistance arteries. In Rat1 fibroblasts expressing each subtype, immunoreactivity was noted both on the cell surface and in a perinuclear orientation. Intense α1B-adrenoceptor immunostaining was similarly localized in cultured femoral and renal vascular smooth muscle cells. Although the cellular localization appeared to be the same, immunoreactivity obtained with α1A- and α1D-adrenoceptors was much less intense than that with the α1B-adrenoceptor. The α1A-adrenoceptor selective agonist A-61603 was 22-fold more potent in activating renal artery contraction when compared with the femoral artery. The expression of each α1-adrenoceptor was significantly decreased by in vivo application of antisense oligonucleotides targeted against each subtype. Inhibition of the expression of only one, the α1A in renal and the α1D in femoral arteries, reduced the contractile response to naphazoline. The results show: 1) subtype-selective antibodies can be used in tissues and cell culture to localize the α1-adrenoceptor subtypes, 2) in addition to expression on the cell surface, the α1-adrenoceptors are expressed intracellularly, and 3) despite expression of all adrenoceptors, a single subtype mediates the contractile response in the femoral and renal arteries.
Footnotes
-
Send reprint requests to: Dr. Michael T. Piascik, Ph.D., Vascular Biology Research Group, Department of Pharmacology, The University of Kentucky College of Medicine, 800 Rose Street, Lexington, Kentucky 40536-0084. E-mail: mtp{at}pop.uky.edu
-
↵1 This work was supported by National Institutes of Health Grants HL-38120 (M.T.P.), HL-56910 (R.W.H.), and HL-52544 (D.M.P.), and a grant-in-aid (M.T.P.) and an Established Investigator Award (D.M.P.) from the American Heart Association.
- Abbreviations:
- AR
- adrenoceptor
- DMEM
- Dulbecco’s modified Eagle’s medium
- FITC
- fluorescein isothiocyanate
- ICC
- immunocytochemistry
- PSS
- physiological saline solution
- SNK
- Student-Newman-Kuel’s
- Received September 30, 1998.
- Accepted March 1, 1999.
- The American Society for Pharmacology and Experimental Therapeutics
JPET articles become freely available 12 months after publication, and remain freely available for 5 years.Non-open access articles that fall outside this five year window are available only to institutional subscribers and current ASPET members, or through the article purchase feature at the bottom of the page.
|