Distribution of 125I-labelled insulin-binding sites in peripheral tissues of the normal and diabetic rat: an autoradiographic study.
In-vitro autoradiography was used to demonstrate the regional distribution of 12I-labelled insulin-binding sites in the liver, kidney and heart of normal rats and rats made diabetic with streptozotocin. The distribution of insulin-binding sites in the liver of control rats was uniformly high, while in the kidney of control rats there was weak 125I-labelled insulin binding in the medulla and dense binding in the cortex. In the hearts of control rats a high density of 125I-labelled insulin-binding sites was evident both in the atrial and ventricular muscle. Non-ketotic diabetes mellitus caused a marked increase in 125I-labelled insulin-binding sites in both the liver and kidney with the former tissue exhibiting a time-dependent (7 to 62 days) increase. There was no apparent effect of diabetes on insulin-binding sites in the heart. Since experimental diabetes causes (1) a decrease in circulating insulin concentration and (2) impaired insulin action at many target tissues, the increase in 125I-labelled insulin-binding sites observed in the present study may represent a compensatory 'up regulation' of insulin receptors.
Thompson
C S
CS
Department of Physiology, Royal Free Hospital School of Medicine, London.
Sykes
R M
RM
Muddle
J
J
Dashwood
M R
MR
D000818:Animals; D001345:Autoradiography; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism*; D007328:Insulin / Q000378:metabolism; D007457:Iodine Radioisotopes; D007668:Kidney / Q000737:chemistry / Q000378:metabolism*; D008099:Liver / Q000737:chemistry / Q000378:metabolism*; D008297:Male; D009206:Myocardium / Q000737:chemistry / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D011972:Receptor, Insulin / Q000378:metabolism*
D007328:Insulin; D007457:Iodine Radioisotopes; D011972:Receptor, Insulin