1. Radioimmunoassay for rat B-type natriuretic peptide (BNP-45)
I R Sarda, D A Wigle, T G Flynn, S C Pang J Immunoassay. 1993 Sep;14(3):167-82. doi: 10.1080/15321819308019847.
Rat BNP-45 is the main circulating form of BNP in rat plasma. To understand the role of BNP in physiological and pathophysiological conditions, a specific radioimmunoassay (RIA) for the quantitative determination of the peptide in plasma and tissues is necessary. An assay using rBNP-45 as the standard in conjunction with antisera directed against this peptide has not been described in the literature, though some investigators have reported values ranging from 0.73-2.0 pmol/L using either BNP-26 or BNP-32 as the standard peptide. Unfortunately, these forms of BNP do not exist in rat plasma. In our studies, we have developed a specific RIA for rBNP-45 using rBNP-45 as the standard peptide and Tyro-rBNP-45 as the radioligand. We have used two specific antisera for assay purposes; one against rBNP-45, and the second to a peptide composed of the first 20 amino acids of rBNP-45 (rBNP[1-20]). The recovery of various amounts of rBNP-45 added to control plasma was 50-80% depending on the method of extraction and purification. The interassay and intraassay coefficients of variation were 12% and 6% respectively. Values obtained were similar for blood sampled by either cardiac puncture, decapitation, or aortic puncture. The method was used to measure rBNP-45 in the plasma of normal (WKY) and Spontaneously Hypertensive (SHR) rats. The values obtained were 5.46 +/- 0.43 and 19.6 +/- 2.36 pmol/L respectively. The rat atrial natriuretic peptide (ANP[99-126]) values in the same extracts were 23.2 +/- 0.45 and 51.6 +/- 3.16 pmol/L.
2. Chronic ethanol treatment increases the circulating plasma levels of B-type natriuretic peptide (BNP-45) in the rat
D A Wigle, S C Pang, J D Watson, I R Sarda, N N Radakovic, T G Flynn Am J Hypertens. 1993 Aug;6(8):719-22. doi: 10.1093/ajh/6.8.719.
Chronic ethanol ingestion is associated with a number of cardiovascular disorders, including stroke, heart failure, and hypertension. Given that the regulation of A-type natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) is known to be altered in both congestive heart failure and essential hypertension, we have investigated the regulation of BNP under the influence of ethanol ingestion. Sprague-Dawley rats were given ethanol in drinking fluid for a 6-week period, while a weight-matched liquid-restricted group received an equivalent volume of ethanol-free solution. Plasma BNP levels were increased in ethanol-treated animals relative to both liquid-restricted and normal control groups. No changes in cardiac BNP gene expression were observed, but an increased trend in atrial tissue BNP levels was evident. No changes in either the mRNA, tissue, or plasma levels of ANP were evident. These results suggest a differential regulation of natriuretic peptides under the influence of ethanol, and implicate chronic ethanol ingestion as a further clinical condition under which the plasma levels of a natriuretic peptide may be elevated.
3. Expression of B-type natriuretic peptide-45 (BNP-45) gene in the ventricular myocardial induced by systemic chronic hypoxia
Frans Ferdinal, Franciscus D Suyatna, Septelia Inawati Wanandi, Mohamad Sadikin Acta Med Indones. 2009 Jul;41(3):136-43.
Aim: To investigate the expression of B-type natriuretic peptide-45 (BNP-45) gene which was induced by systemic chronic hypoxia, and whether these changes would be different from BNP-45 protein in the plasma and its mRNA in the ventricular myocardial. This study also aimed to test the hypothesis that systemic chronic hypoxia may cause heart failure. Methods: Although clinical use of BNP as a biomarker in heart failure is increasing, the specificity of BNP for heart failure is not robust, suggesting that other mechanisms beyond simple ventricular stretch stimulate BNP release. Plasma BNP levels were markedly increased in patients with coronary artery disease but without concomitant left ventricular dysfunction. Thus, elevated BNP levels do not necessarily reflect heart failure but may also result from cardiac ischemia. Sprague-Dawley male rats, weighing 220-250 g at the time of recruitment were randomly divided into 7 groups (n = 4 per group), the control normoxia group was exposed to room air, while the hypoxia group were caged in a plexiglass hypoxic chamber (8%O2 and 92% N2) for 1, 3, 7, 14, 21, and 28 days, respectively. Results: Our data clearly showed that plasma BNP-45 and ventricular BNP-45 mRNA concentration were markedly increased which reached its peak on day 21 after treatment. Conclusion: Regulation of BNP-45 gene expression occurred at transcription as well as post-transcription level. Systemic chronic hypoxia could result in heart failure, especially when the hypoxia is severe and prolonged.
