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Biomedical subjects

R A Sutton

Publications and source records attributed to R A Sutton.

At least 91 records · Page 5Linked to original sources
PubMed1979

Effects of parathyroid hormone on electrolyte transport in the hamster nephron.

Recollection micropuncture and clearance studies were carried out on thyroparathyroidectomized hamsters to clarify the localization of the effects of parathyroid hormone (PTH) on renal electrolyte transport. The clearance data confirmed that PTH inhibits phosphate and enhances calcium and magnesium reabsorption. These effects appeared to result from actions of the hormone in several parts of the nephron. In the proximal tubule PTH did not affect H2O reabsorption but inhibited phosphate reabsorption ((TF/P)PO4 increased from 0.46 +/- 0.04 to 0.57 +/- 0.03, P less than 0.02) and appeared to enhance calcium and magnesium reabsorption ((TF/UF)Ca decreased from 1.41 +/- 0.07 to 1.25 +/- 0.06, P less than 0.001, and (TF/UF)Mg from 1.66 +/- 0.10 to 1.51 +/- 0.08, P less than 0.05; in control animals (TF/UF)Ca increased from 1.51 +/- 0.10 to 1.65 +/- 0.11, P less than 0.01). PTH further inhibited phosphate reabsorption and enhanced calcium and magnesium reabsorption between the late proximal and early distal sites of puncture. Comparison of fractional deliveries of calcium and magnesium from the late distal tubule with their fractional excretions suggests an additional effect beyond the distal puncture site. The phosphaturic, but not the calcium- and magnesium-retaining, effects of PTH were abolished by a 16-h fast.

Animals↗
PubMed1977

A comparative study of dextran-70, warfarin and low-dose heparin for the prophylaxis of thrombo-embolism following total hip replacement.

In a randomized, controlled clinical study, dextran-70, warfarin, or low-dose heparin were administered to patients undergoing total hip replacement on one surgical unit in an attempt to prevent deep venous thrombosis and pulmonary embolism. Calf vein thrombosis was detected by the 125I-fibrinogen uptake test. None of the methods prevented calf vein thrombosis (dextran-70, 51%; warfarin, 58-6%; heparin, 52-6%). Pulmonary embolism was completely prevented in patients treated with warfarin but occurred in 4% of patients treated with dextran-70 and 15-5% of those treated with low-dose heparin. The incidence of complications of therapy was small and comparable in each group. It is suggested that calf vein thrombosis is a frequent and in itself a non-serious complication of total hip replacement surgery and that emphasis might be placed more usefully on prevention of pulmonary embolism.

Aged↗
PubMed1976

Effects of parathyroid hormone on sodium and calcium transport in the dog nephron.

1. The effect of purified bovine parathyroid hormone on renal tubular reabsorption of sodium and calcium has been studied by micropuncture in intact and recently thyroparathyroidectomized dogs. 2. Parathyroid hormone increased the rejection of sodium and calcium proportionately at the late proximal tubule in both intact and operated dogs. 3. In both groups of dogs, there was increased delivery of sodium and calcium to the distal tubule after the hormone. However, the Ca/Na ratio decreased, suggesting some selective enhancement of calcium reabsorption before the superficial distal puncture site. 4. In the final urine, the Ca/Na ratio decreased highly significantly in both groups of dogs, indicating a further selective effect of parathyroid hormone on calcium reabsorption in or beyond the distal convoluted tubule.

Absorption↗
PubMed1975

Interrelationship of chlorothiazide and parathyroid hormone: a micropuncture study.

Sodium and calcium are normally reabsorbed in parallel in the renal tubule. Both parathyroid hormone (PTH) and thiazide diuretics may influence this relationship. This study was designed to show whether the dissociation of Na from Ca transport produced by thiazides is dependent upon the presence of PTH. Hydropenic thyroparathyroidectomized (TPTX) dogs were given chlorothiazide alone and together with PTH. Chlorothiazide alone significantly increased fractional excretion of sodium (0.5 +/- 0.3-5.6 +/- 0.3%) and calcium (0.74 +/- 0.18-1.4 +/- 0.24%). However, the Ca/Na excretion ratio fell markedly from 1.57 to 0.24%. Micropuncture revealed this dissociation to occur at the distal tubule. Proximal reabsorption of water, sodium, and calcium were inhibited to an equal extent. However, distal fractional sodium reabsorption fell 10% whereas calcium reabsorption remained unchanged following chlorothiazide administration in TPTX animals. When phosphaturic doses of PTH were administered with chlorothiazide, no significant changes were observed in calcium or sodium reabsorption. It is concluded that PTH plays no role in the dissociation of sodium from calcium reabsorption resulting from acute chlorothiazide administration.

Animals↗
PubMed1973

Micropuncture study of diuretic effects on sodium and calcium reabsorption in the dog nephron.

A close relationship has been observed between the clearance rates of sodium and calcium under a variety of diuretic conditions. The thiazide diuretics act differently in dissociating the renal tubular reabsorption of sodium and calcium. This phenomenon has been further investigated using recollection micropuncture and clearance techniques in a group of 14 dogs subjected to three consecutive experimental phases: expansion to 3% of body weight (BWt) with Ringer's solution, chlorothiazide infusion at 20 mg/kg/h, and furosemide in a prime of 10 mg/kg/ and a 10 mg/kg/h infusion. Diuretic losses were balanced with infusion of equal volumes of Ringer's solution throughout the experiment. Chlorothiazide increased the fractional excretion (FE) of sodium almost threefold while FE(Ca) was not significantly altered. Furosemide increased FE(Na) and FE(Ca) to an approximately equal, and more marked, degree. This dissociation of sodium and calcium reabsorption after chlorothiazide was also evident in the superficial distal tubule, where (tubule fluid/plasma sodium) (TF/P(Na)) increased from 0.32 to 0.49 (P < 0.01) and TF/(ultrafiltrate)UF(Ca) was unchanged (0.35-0.31). Furosemide markedly reduced the transtubular concentration gradient for both sodium (0.86) and calcium (0.94). TF/P(Inul in) decreased progressively from 3.79 to 2.78 to 2.33 in three phases. In the late proximal tubule, chlorothiazide induced a fall of TF/P(Inul in) from 1.57 to 1.44 (P < 0.01), but the ratio TF/UF(Ca): TF/P(Na) was unchanged. Furosemide had no significant proximal effect. It is concluded that acute administration of chlorothiazide reduces sodium reabsorption in the distal hephron, presumably the cortical diluting segment, without affecting calcium reabsorption.

Animals↗
PubMed1970

Plasma magnesium concentration in primary hyperparathyroidism.

The plasma magnesium concentration has been determined in 73 patients with primary hyperparathyroidism. In most patients it lay within the normal range (1.7-2.3 mg./100 ml.), but in five it was less than 1.6 mg./100 ml. These patients had relatively high urinary magnesium outputs, and one of them, studied in greater detail, failed to retain parenterally administered magnesium. Hence hypomagnesaemia in hyperparathyroidism may be associated with a defect in renal magnesium conservation, which may be reversible.

Adult↗