High expression of IGF-I receptors compared to insulin receptors in human mammary artery

• Aims/hypothesis: Cultured endothelial and vascular smooth muscle cells from different vascular beds express several fold more IGF-I receptors (IGF-IR) than insulin receptors (IR). The aim of this study was to investigate the gene expression of IR and IGF-IR in tissue samples from the left internal mammary artery (LIMA) to see if there is a higher gene expression of IGF-IR compared to IR in arterial tissue in vivo. Methods: Samples from LIMA (n=16) were obtained at coronary bypass surgery, immediately frozen in liquid nitrogen and stored at -70°C until analysis. The samples were thawed, placed on ice and dissected free from surrounding connective tissue and fat, homogenized and total RNA was extracted. Receptor mRNA was analyzed by quantitative real time RT-PCR and comparison of CT-values. Results: LIMA samples were obtained from 16 patients, 10 non-diabetic and 6 diabetic patients. Gene expression of IGF-IR was detected in all LIMA samples, however, the insulin receptor mRNA was under the detection limit in 4 samples. Compared to IR the gene expression of IGF-IR was 36 fold higher (n=12. p <0.0001). The relative gene expression of IGF-IR to IR in LIMA from non-diabetic patients (n=9) and diabetic patients (n=3) was similar, 39 and 32 fold, respectively. Conclusions/interpretation: Our results in mammary artery samples indicate that IGF-IR are more expressed than IR in arterial tissue in vivo.

Nyckelord

Receptors

insulin

IGF-I

LIMA

gene expression

RT-PCR

MEDICINE

MEDICIN

Publikations- och innehållstyp

vet (ämneskategori)

ovr (ämneskategori)