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C J Edmonds

Publications and source records attributed to C J Edmonds.

At least 73 records · Page 4Linked to original sources
PubMed1976

Effect of aldosterone on lithium permeability of rat colon mucosa.

The effect of aldosterone on the ionic composition of colonic epithelial cells and on lithium absorption rate was studied by experiments on rats in vivo. Aldosterone considerably increased the rate of sodium absorption without measurably altering the sodium and potassium content of the epithelium. Aldosterone did not alter the electrical resistance of the tissue. With lithium in the lumen, the net sodium fluxes in the colon were similar in normal and aldosterone-stimulated rats but the rate of diffusion of lithium across the epithelium was greater in the aldosterone-stimulated group. The amount of lithium accumulating in the epithelial layer was also considerably increased by aldosterone stimulation. Aldosterone appears to increase the permeability of the mucosal (luminal) barrier allowing increased entry of lithium into the colonic epithelial cells.

Aldosterone↗
PubMed1975

Total body potassium and body fat estimation in relationship to height, sex, age, malnutrition and obesity.

1. Total body potassium was estimated by 40-K measurement with a high-sensitivity whole body counter in normal individuals over a wide age range and in patients who were obese or were grossly wasted as a result of various conditions which restricted food intake. 2. Potassal males and females, but when individuals of different age groups were matched for height, a significant fall in total body potassium with increasing age was observed only in males. Total body potassium of females was about 75% that of males of similar height when young, the sex difference decreasing with ageing. In the normal population, total body potassium was significantly correlated with height and with weight; regression equations for various relationships are given. 3. Fat-free mass was estimated from total body potassium, values of 65 and 56 mmol of potassium/kg fat-free mass being used for males and females respectively. Body fat estimated by this method correlated well with skinfold measurements over a wide range of body weight but in malnourished individuals having inadequate food intake there was considerable fat-free mass from total body potassium appear unsatisfactory in malnutrition. Considerable differences between expected and observed values of total body potassium were found in muscular individuals and in normal individuals who were thin but whose body weight was relatively constant. 4. The patients with malnutrition were low both in body fat as estimated by skinfold thcikness and in total body potassium estimated on the basis of height. Plasma potassium was, however, normal and potassium supplements did not increase the total body potassium. 5. Total body potassium of obese individuals was not significantly different from that of normal weight individuals on the basis of height. Total body potassium fell on weight reduction with a very low energy diet of 1260 kJ (300 kcal.) daily but changed little with a 3300 kJ (800 KCAY POTASSIUM WAS BEST PREDICTED FROM THE INDIVIDUAL'S HEIGHT. For those whose body weight was less than expected, the use of weight gave the best prediction but the error was considerable when the weight deviation was large.

Adipose Tissue↗
PubMed1975

The effect of aldosterone and the renin-angiotensin system on sodium, potassium and chloride transport by proximal and distal rat colon in vivo.

1. The roles of aldosterone and angiotensin in the direct control of epithelial sodium transport in vivo have been investigated by measurement of electrical p.d. changes and of the fluxes of sodium, potassium and chloride in rat colon, an organ actively involved in electrolyte homoeostasis. Exogenous angiotensin and aldosterone were given by both short- and long-term infusions and endogenous secretion of the hormones was varied by dietary sodium variation and by nephrectomy and/or adrenalectomy. 2. In vitro angiotensin has been shown to influence colonic salt and water absorption but in the present in vivo experiments administered angiotensin had no significant action on p.d. or on the ionic fluxes of the proximal or distal colon. The increase in p.d. produced by infusing aldosterone was unaffected by giving angiotensin concurrently. The effect of sodium depletion in stimulating sodium absorption and potassium secretion was completely abolished by adrenalectomy but was unaffected by nephrectomy. 3. During prolonged infusion of angiotensin into adrenalectomized rats, a small fall in faecal fluid and sodium content was observed, but this change would have little significance in sodium homoeostasis. 4. Aldosterone and sodium depletion stimulated sodium absorption in both proximal and distal colon but significant increase in potassium secretion was demonstrable only in the distal colon. Bicarbonate secretion (by calculation) was unaffected. In the proximal colon, the increased sodium absorption appeared to be accompanied by increased chloride absorption while in the distal colon it was principally the sodium-potassium exchange that was increased. 5. Adrenalectomy reduced potassium secretion in both proximal and distal colon but sodium absorption was only significantly reduced in the proximal colon. 6. It was concluded that there is no evidence that angiotensin in the living animal has a role as an important salt retaining hormone by direct epithelial action. Aldosterone has a considerable effect which is independent of the presence of angiotensin, and which differs in proximal and distal colon in regard to the relative effects on chloride absorption and potassium secretion.

Adrenalectomy↗
PubMed1975

Electrical potential difference, sodium absorption and potassium secretion by the human rectum during carbenoxolone therapy.

The transmucosal electrical potential difference (pd) and the sodium and potassium net fluxes were measured in the rectum of subjects taking carbenoxolone. There was a rise in transmucosal pd persisting throughout treatment in all subjects which was accompanied by an increase in sodium absorption and potassium secretion. Comparison of the pd changes produced by carbenoxolone with those due to the mineralocorticoid 9-alpha-fluorocortisol showed that carbenoxolone had about 1/1000th the potency on a weight basis and the two drugs appeared to be additive in their effects. Topical instillation of carbenoxolone into the rectum produced an elevation of pd which persisted for three days. Amiloride and bendrofluazide did not interfere with these actions of carbenoxolone but spironolactone abolished them. One patient who developed fluid retention and hypokalaemia had a rectal pd similar to that of the other patients who had no side effects.

Adult↗
PubMed1974

Salts and water.

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Animals↗
PubMed1974

Electrical potential difference and absorption of water, sodium, and potassium by the terminal ileum of ileostomy patients.

Measurements of electrical potential difference (pd) and of absorption by a dialysis method were carried out in the terminal ileum of patients with an ileostomy. The pd measured with saline in the lumen and at a few centimetres within the stoma averaged 9.2 mV, lumen negatively charged. The pd values were similar whether the ileostomy had been recently or long established. The pd rose considerably when glucose was added to the luminal solution, the maximum effect being attained with a concentration of 40 mmol/1. With a saline bicarbonate solution (Na 145 or 140 m-equiv/1, K 5, or 10 m-equiv/1) in the dialysis tube, considerable absorption of fluid and sodium was demonstrable with little change in sodium concentration. Potassium secretion occurred with the lower, and absorption with the higher, concentration. The final luminal potassium concentration reached was consistent with a passive distribution between blood and lumen.

Adult↗
PubMed1973

Electrical potential difference and sodium and potassium fluxes across rectal mucosa in ulcerative colitis.

The transmucosal electrical potential difference (pd) and the sodium and potassium flux rates (using a dialysis method) have been measured in the rectum and distal sigmoid colon of patients with ulcerative colitis and compared with measurements made in individuals having normal bowel function. In active colitis, a very low transmucosal pd was found and was associated with loss of the characteristic ability of the mucosa to absorb sodium against considerable electrochemical gradients; a marked increase in the plasma-to-lumen sodium flux rate, suggesting increased leakiness of the mucosa; and loss of the active sodium absorption mechanism. In resolving colitis, the pd was higher and all these changes of sodium transport tended to return towards normal. With full recovery, epithelial function was normal to the present tests. Potassium secretion rate showed little difference at various stages of the disease, but the nearly normal secretion of potassium in ulcerative colitis when the pd was low suggested that potassium loss to the lumen was excessive. Mucus collected from patients with ulcerative colitis had a relatively high sodium and potassium content. Measurement of pd and absorption by using a dialysis tube offers a simple means of rapid assessment of mucosal functional integrity.

Adult↗