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Biomedical subjects

N B Argent

Publications and source records attributed to N B Argent.

8 recordsLinked to original sources
PubMed1992

Metabolic clearance rate of arginine vasopressin in severe chronic renal failure.

1. The metabolic clearance rate of arginine vasopressin was determined using a constant infusion technique in normal subjects and patients with chronic renal failure immediately before commencing dialysis. Endogenous arginine vasopressin was suppressed in all subjects before the infusion with a water load. 2. Plasma arginine vasopressin concentrations were determined using a sensitive and specific radioimmunoassay after Florisil extraction. The detection limit of the assay was 0.3 pmol/l, and intra- and inter-assay coefficients of variation at 2 pmol/l were 9.7% and 15.3%, respectively. 3. In normal subjects, the metabolic clearance rate was determined at two infusion rates producing steady-state concentrations of arginine vasopressin of 1.3 and 4.4 pmol/l. In the patients with renal failure, a single infusion rate was used, producing a steady-state concentration of 1.5 pmol/l. 4. At comparable plasma arginine vasopressin concentrations, metabolic clearance rate was significantly reduced in patients with renal failure (normal 1168 +/- 235 ml/min versus renal failure 584 +/- 169 ml/min; means +/- SD; P < 0.001). 5. Free water clearance was significantly reduced in normal subjects during the arginine vasopressin infusion from 8.19 +/- 2.61 to -1.41 +/- 0.51 ml/min (P < 0.001), but was unchanged in the patients with renal failure after attaining comparable plasma arginine vasopressin concentrations. 6. In normal subjects there was a small but significant fall in metabolic clearance rate at the higher steady-state arginine vasopressin concentration (1168 +/- 235 ml/min at 1.3 pmol/l versus 1059 +/- 269 ml/min at 4.4 pmol/l; P = 0.016).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Osmoregulation of thirst and vasopressin release in severe chronic renal failure.

Subjects with severe chronic renal failure (CRF) have higher plasma concentrations of arginine vasopressin (AVP) than normal subjects, and some develop severe thirst. Eight patients with CRF and seven matched controls underwent hypertonic saline infusion to explore the relationship of thirst and plasma AVP with plasma osmolality. Differences in urea concentration between the two groups were controlled for by correcting measured osmolality to a urea of zero. Linear regression analysis of the relationships between plasma AVP and thirst with plasma osmolality (corrected for urea) was performed. Mean results were: control, pAVP = 0.26 (pOsmc - 283.7) versus CRF, pAVP = 0.72 (pOsmc - 282.0); and control, thirst = 4.0 (pOsmc - 279.4) versus CRF, thirst = 3.5 (pOsmc - 281.8). The apparent sensitivity (slope) of AVP release was greater in severe CRF than in normal controls (P = 0.04). There was no significant difference between the groups in thirst sensitivity, threshold for thirst onset and threshold for AVP release. Osmoregulated thirst was normal in severe CRF, but increasing osmolality leads to higher concentrations of AVP than would be expected.

Adult↗
PubMed1991

Chronic hypernatremia due to impaired osmoregulated thirst and vasopressin secretion.

We report the case of a young man who became adipsic following a subarachnoid hemorrhage and subsequently had two episodes of life-threatening hypernatremia. Investigations demonstrated that he had defective osmoregulated thirst and AVP release, but normal AVP responses to hypotension and nausea. There is also evidence that he had intact baroregulated thirst. We discuss the results of our investigations in the context of current models of hypothalamic-neurohypophysial function.

Adult↗
PubMed1990

Immunoreactive vasopressin in end stage renal failure.

Patients with end stage renal failure have been shown to have higher basal concentrations of plasma arginine vasopressin than subjects with normal renal function. Immunoreactive vasopressin was detected in plasma from patients with severe chronic renal failure and a healthy subject at an elution volume identical to that previously determined with synthetic vasopressin. Assay of all fractions yielded identical chromatograms in the renal failure and healthy control groups. We conclude that the plasma immunoreactive vasopressin in end stage renal failure plasma coelutes with synthetic vasopressin and that the elevated concentrations found in these patients are not due to non-specific depression of binding in the vasopressin radioimmunoassay by circulating substances in renal failure.

Adult↗