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Renal metabolism of C-peptide in patients with early insulin-dependent diabetes mellitus
Renal metabolism of C-peptide was studied in 6 patients with early insulin-dependent diabetes mellitus (IDDM) with residual beta cell activity and in 11 nondiabetic subjects by the arterial-venous difference technique both in the postabsorptive state and for 80 min after ingestion of an amino acid mixture (0.8 g/kg). Urinary C-peptide (Cp) excretion, glomerular filtration rate and renal plasma flow were also measured. In the postabsorptive state in IDDM, renal uptake of Cp is reduced, while its urinary excretion and clearance are significantly increased. As a result, net renal extraction is markedly reduced. In contrast to controls, renal uptake and net extraction of C-peptide after amino acid ingestion do not increase in patients; the peritubular uptake evident in normal subjects is not detectable. Urinary excretion and clearance of Cp remain significantly higher in IDDM patients. In both groups, renal uptake of C-peptide is directly related to its renal load: however, in IDDM, the increase in Cp uptake for each increment in renal load is 35% lower than in controls (p < 0.001). Furthermore, as opposed to controls, urinary Cp excretion is not correlated with its arterial levels. Therefore IDDM patients have marked defects in renal handling of endogenous Cp, regarding both the amount metabolized by renal tissue and that reabsorbed by tubular cells. These data indicate an early alteration in the diabetic kidney that also impairs the reliability of urinary Cp evaluation as an index of residual beta cell activity in IDDM patient
Splanchnic exchange of amino acids after amino acid ingestion in patients with chronic renal insufficiency
Splanchnic exchange (net uptake or release) of amino acids (AAs) was evaluated by measuring arterial-hepatic venous differences for AAs and hepatic blood flow in patients with chronic renal insufficiency (CRI) and control subjects before and for 70 min after the ingestion of an AA mixture simulating an animal protein meal. In CRI after AA ingestion, splanchnic exchange area for total nonessential AAs (NEAAs) is increased 135% over control subjects because of an augmented escape of proline, glutamate, serine, glycine, alanine, and cyst(e)ine; contrarily, glutamine shows an increased splanchnic uptake. Splanchnic exchange area for total essential AAs (EAAs) is increased only by 67% over controls because of a higher escape of threonine, isoleucine, phenylalanine, and histidine. Abnormalities in arterial areas for AAs parallel those in splanchnic areas except for glutamine and isoleucine. Data indicate that in CRI, at least for 70 min after an AA meal, splanchnic organs metabolize abnormally ingested AAs and export an increased and unbalanced bulk of AAs, severely affecting postprandial arterial profile of AA
EFFETTI DELLE VARIAZIONI DEL pH DEL BAGNO DI DIALISI SULL'EQUILIBRIO ACIDO-BASE (EAB) DEI PAZIENTI IN CORSO DI EMODIALISI
INFLUENCE OF ARTERIAL BRANCHED-CHAIN AMINOACID CONCENTRATION ON CEREBRAL UPTAKE OF BRANCHED-CHAIN AMINO ACIDS AND GLYCINE IN CHRONIC RENAL INSUFFICIENCY
NELL'INSUFFICIENZA RENALE CRONICA, L'INGESTIONE DI PROTEINE E' CAUSA DI UN ALTERATO APPORTO DI AMINOACIDI ALL'ENCEFALO?
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