In Vitro Micro-Autoradiography of Atrial Natriuretic Peptide in Biopsy Specimens from Patients with Renal Diseases

Title: In Vitro Micro-Autoradiography of Atrial Natriuretic Peptide in Biopsy Specimens from Patients with Renal Diseases
Authors: Ogura, Toshio; Asano, Naoko; Katayama, Eriko; Oishi, Tetsuya; Mimura, Yukari; Hironaka, MD, Kazue; Kashihara, Naoki; Makino, Hirofumi; Ota, Zensuke; Ogawa, Norio
Publisher: Journal of Medicine
Date Published: 1994
Reference Number: 116
We investigated the localization and density of atrial natriuretic peptide (ANP) receptors in human renal biopsy specimens by using in vitro micro-autoradiography (ARG) of [125I]-alpha-human (1-28) ANP. In a preliminary study, we measured the effect of storing tissue samples on ANP binding, using in vitro micro-ARG of Wistar rat kidney under optimal conditions. Duration of the preservation period did not affect ANP binding to renal tissue until samples had been stored at -30 degrees C for two years. A total of 11 human renal tissues were used to assay binding of ANP-ARG, including normal tissue obtained after nephrectomy because of renal cancer. ANP binding occurred predominantly within the glomerulus and, to a lesser extent, in the tubular region both in rat kidney sections and in human renal biopsy specimens. The density of ANP binding, calculated by counting grains in fixed areas, was compared with normal and pathological tissues. The density of grains tended to decrease in patients with renal dysfunction and hypertension except for one case of IgA nephropathy with normal renal function and blood pressure. The density of grains increased in a patient with nephrogenic diabetes insipidus. In the present study, we have established a method that uses in vitro micro-ARG for assessing ANP binding in human biopsy specimens.

This translation by the NDI Foundation is to assist the lay reader. To provide a clear, accessible interpretation of the original article, we eliminated or simplified some technical detail and complicated scientific language. We concentrated our translation on those aspects of the article dealing directly with NDI. The NDI Foundation thanks the researchers for their work toward understanding and more effectively treating this disorder.
© Copyright NDI Foundation 2007 (JC)

Atrial natriuretic peptide (ANP) is a hormone that promotes excretion of sodium in urine and regulates kidney, heart and blood vessel stability. ANP, to be effective, needs specific biological structures called receptors to receive their hormonal messages. The hormones bind to specific receptors called ANP receptors and transfer their information to them. These ANP receptors are located on the kidney, smooth muscle cells, adrenal glands and brain. Ogura, et al., investigated changes in ANP receptors in people who had suffered kidney disease. They determined the location and density of kidney ANP receptors by using a process called autoradiography (ARG) on tissue specimens from patients with kidney diseases. Then they compared them with the locales and densities of ANP receptors in kidney tissues from people with healthy kidneys.

They examined diseased kidney tissues from 11 people who had kidney disease, finding that ANP binding sites (the places where the ANP meets the ANP receptor) occurred predominately within the glomeruli -- little filters in the kidney that allow certain dissolved substances from the bloodstream into little tubes (tubules) in the kidney, but prevent cells and large proteins from crossing over. The authors also found that ANP binding occurred, but much less frequently, in kidney tubules. Examination of healthy kidney tissues revealed the same distribution pattern for ANP binding.

Ogura, et al., found fewer glomerular ANP receptors in kidney tissue from patients with kidney dysfunction and hypertension than in tissue from healthy people. There were two exceptions: one case of IgA nephropathy (where the patient had normal kidney function and blood pressure) where the glomerular ANP receptor count was normal, and one case of nephrogenic diabetes insipidus (NDI) where the ANP density was greater than normal. The authors are using their method of in vitro micro-ARG to assess ANP binding in human tissue specimens to further investigate changes in ANP receptor binding.