Urine and plasma levels of uroguanylin and its molecular forms in renal diseases

Urine and plasma levels of uroguanylin and its molecular forms in renal diseases. Uroguanylin activates the intestinal and possibly the renal guanylate cyclase C receptor, and stimulates Cl− secretion. We developed a sensitive radioimmunoassay (RIA) for human uroguanylin and measured its concentration in the urine and plasma. Twenty-four-hour urinary excretion of immunoreactive (ir-) uroguanylin for persons with a high-salt diet (10 g/day) was 137.8 ± 14.4 pmol/day, significantly higher than that for persons with a low-salt diet (7 g/day, 95.1 ± 16.3 pmol/day, P < 0.05). There were significantly positive correlations between the urinary excretion of ir-uroguanylin and Na+, Cl−, K+ or cyclic GMP (cGMP). We demonstrated the presence of messenger RNA of guanylate cyclase C in the medulla of human kidney. The concentration of plasma ir-uroguanylin significantly correlated with that of serum creatinine (r = 0.71, P < 0.001). Biologically active uroguanylin-16 accounted for 99% of the endogenous uroguanylin molecules in normal urine and 60% in plasma, the remainder being the 10kDa precursor. The precursor content increased in the urine and plasma as the severity of renal impairment increased. These findings suggest that bioactive uroguanylin-16 is involved in the regulation of electrolyte homeostasis and that the kidney participates in the metabolism and excretion of uroguanylin

Purification and characterization of PAMP-12 (PAMP[9–20]) in porcine adrenal medulla as a major endogenous biologically active peptide

AbstractProadrenomedullin N-terminal 20 peptide (PAMP-20) is a potent hypotensive peptide processed from the adrenomedullin (AM) precursor. We developed a specific radioimmunoassay which recognizes the C-terminal region of PAMP-20. Using this radioimmunoassay, the distribution of immunoreactive (ir-) PAMP was determined in porcine tissues. High concentrations of ir-PAMP were observed in the adrenal medulla and in the atrium, and these values were comparable to the corresponding concentrations of ir-AM. The concentration of ir-PAMP was almost the same as that of ir-AM in the kidney, while ir-PAMP was significantly lower than ir-AM in the ventricle, lung, and aorta. Reversed-phase high performance liquid chromatography in each porcine tissue sample revealed that two major peaks of ir-PAMP existed: one emerged at a position identical to that of authentic porcine PAMP-20; the other unknown peak was eluted earlier. The unknown peptide was purified to homogeneity from porcine adrenal medulla, and its complete amino acid sequence was determined. This peptide was found to be PAMP[9–20] with a C-terminal amide structure, and was named PAMP-12. Intravenous injections of PAMP-12 in anesthetized rats showed a significant hypotensive effect in a dose-dependent fashion, and the effect was comparable to that of PAMP-20. These data indicate that PAMP-12, a major component of ir-PAMP, is processed from the AM precursor, as is PAMP-20, and may participate in cardiovascular control

Combined use of brain natriuretic peptide and C-reactive protein for predicting cardiovascular risk in outpatients with type 2 diabetes mellitus

Toshihiro Tsuruda1, Johji Kato2, Takahiro Sumi1, Kazuya Mishima1, Hiroyuki Masuyama1, Hiroyuki Nakao3, Takuroh Imamura1, Tanenao Eto1, Kazuo Kitamura11Department of Internal Medicine, Circulatory and Body Fluid Regulation, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan; 2Frontier Research Center, University of Miyazaki, Miyazaki, Japan;&nbsp;3Department of Public Health, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan Abstract: Appropriate tools are necessary for predicting cardiovascular events in patients with diabetes mellitus because of their high incidence. In this study, we assessed whether a combination of brain natriuretic peptide (BNP) and C-reactive protein (CRP) measurement were useful prognosticators in patients with type 2 diabetes mellitus. One hundred and nine patients with type 2 diabetes mellitus, aged 52 to 93 years, were examined at outpatient clinics for blood, urinary samples, and echocardiography. They were then followed prospectively. During the average follow-up period of 30 months (range, 3 to 37), 15 patients (14%) had cardiovascular events: This was the first event in 5 patients and a recurrence in 10. Cox regression analysis showed that the past event (hazard ratio [HR] 4.819 [95% confidence interval (CI): 1.299&ndash;17.881]; p = 0.019) and plasma BNP level (HR 1.007 [95% CI: 1.002&ndash;1.012]; p = 0.010] were independently significant factors for the cardiovascular events during the follow-up period. Patients with plasma BNP &ge;53 pg/mL and CRP &ge;0.95 mg/dL demonstrated the highest incidence in cardiovascular event, compared to those categorized into either or both low levels of BNP and CRP. This study suggests that combination of plasma BNP and CRP measurement provides the additive prognostic information of cardiovascular events in patients with type 2 diabetes mellitus.Keywords: diabetes mellitus; natriuretic peptide; inflammation; mortality and morbidit