PubMed Health⌕ Search

Biomedical subjects

J T Higgins

Publications and source records attributed to J T Higgins.

At least 37 records · Page 2Linked to original sources
PubMed1977

Diagnosis of secondary forms of hypertension. A comprehensive protocol.

An efficient protocol for the evaluation of hypertensive cases included renal arteriography, suppression and stimulation of the renin-aldosterone system, and, when indicated, renal venous renin measurements. It permitted identification of 38 patients with renal artery stenosis, 28 with primary aldosteronism, and 51 with high renin, 92 with normal renin, and 27 with low renin essential hypertension.

Adolescent↗
PubMed1977

Natriuretic response to saline infusion in normotensive and hypertensive man. The role of renin suppression in exaggerated natriuresis.

Previous studies have reported an exaggerated natriuresis in hypertensive man; however, a systematic appraisal of this response in various forms of hypertension has not been made. We measured fractional excretion of sodium (FENa) during a four hour intravenous infusion of 2 liters normal saline in 162 normal subjects and 120 hypertensives. Of these, 13 had primary aldosteronism (ALDO), 19 high renin (HRH), 30 low renin (LRH), and 57 normal renin (NRH) essential hypertension. FENa for normals (1.42%), NRH (1.57%), and HRH (1.46%) was similar. That for LRH (2.56%) and ALDO (4.18%) was elevated compared to the other three subgroups (P less than 0.001). Although the four hour FENa during saline infusion was associated with mean atrterial blood pressure (MABP) within the entire hypertensive population (r = 0.51), when the subgroups of the hypertensive patients were considered separately no association between FENa and MABP was identified. Moreover, the MABP of subjects with HRH was greater (P less than 0.05) than in those with NRH, although the FENa of the two subgroups was similar. Patients with ALDO and LRH have a greater natriuretic response to a salt load than do other subgroups of essential hypertension or normal subjects. The exaggerated natriuresis appears to be a feature of hypertension with renin suppression. The degree of exaggerated natriuresis in not solely a function of an elevated mean arterial blood pressure.

Adolescent↗
PubMed1977

Diagnosis, localization, and treatment of primary aldosteronism.

PA should be suspected in any hypertensive patient with evidence of renin suppression and should be confirmed by demonstration of inappropriate and excessive aldosterone production. Preoperative differentiation of unilateral and bilateral forms of the syndrome should be pursued to identify those patients most likely to benefit from surgical intervention. In patients with apparent bilateral disease, specific medical therapy should be pursued.

Aldosterone↗
PubMed1977

Differences in response to sodium administration in normotensive white and black subjects.

In order to examine possible differences in PRA, PA, and renal electrolyte excretion in normotensive black and white subjects, we studied 68 age-matched subjects: 19 white men, 19 black men, 15 white women, and 15 black women. PRA was measured before and after the infusion of 2 L of normal saline to evaluate suppression of the renin-aldosterone system. The excretion of sodium, potassium, and creatinine in response to the salt load was monitored for 24 hr. PRA and PA measurements were repeated after 2 hr of ambulation on the morning following salt loading. Dietary sodium was then restricted and oral furosemide (120 mg) was administered in order to assess PRA and PA responsiveness to sodium and volume depletion. White and black subjects had similar PRA and PA responses to normal saline and furosemide administration. Over a 24 hr period, black subjects excreted significantly less sodium and potassium following the salt load than did white subjects. The PRA values of black subjects 24 hr following the salt load were significantly suppressed as well. These observations suggest that there may be racial differences in renal sodium excretion reflected by decreased urinary sodium excretion and a relative suppression of PRA following a salt load in black persons.

Adult↗
PubMed1976

Exaggerated natriuresis in the conscious spontaneously hypertensive rat.

In response to an acute saline load, many patients with essential hypertension exhibit an exaggerated natriuresis relative to normotensive controls. In the present study, the urinary responses of conscious,Okamoto-strain, spontaneously hypertensive rats (SHR), and Wistar-Kyoto strain normotensive rats (NTR) to an acute saline load were evaluated to determine if a similar exaggerated natruiresis exists in this form of hypertension. Twelve rats of each strain per group (12 weeks of age) were housed in metabolism cages for 1 week. Systolic blood pressures (tail cuff) were significantly different (206+/- 9 mm. Hg in SHR and 135 +/- 3 mm. Hg in NTR). After a 4-hour control urine collection, 6 ml. of 0.9 per cent sodium chloride were given by gavage. Urine was collected again for 2 hours. Control urinary excretions of sodium, potassium, and creatinine in SHR and NTR were 11.2 +/- 4.8 muEq per hour, 50.1 +/- 7.6 muEq per hour, and 39.9 +/- 5.5 mg. per hour in SHR, and 13.8 +/- 2.4 muEq per hour, 34.9 +/- 5.5 muEq per hour, and 37.5 +/- 7.1 mg. per hour in NTR, respectively. The respective control values for sodium, potassium, and creatinine excretion in the two groups were not significantly different. Following the saline load, sodium and creatinine excretion rates were significantly elevated in both groups of rats. However, the increase in sodium excretion in SHR (60.8 +/- 7.2 MUEq per hour) was more than double and significantly different from that of the NTR (26.6 +/- 3.7 muEq per hour). In contrast, the increments in creatinine excretion in the two groups of rats were not significantly different from each other. In the NTS, urinary potassium excretion was significantly elevated (59.0 +/- 7.9 muEq per hour) whereas in SHR it was not significantly altered (12.0 +/- 8.8 muEq per hour). The change in urinary creatinine excretion as an index of change in glomerular filtration rate suggests that the greater increase in sodium excretion by the SHR was the result of decreased fractional reabsorption of sodium and not the result of a greater increase in glomerular filtration rate. The exaggerated natriuretic response to salt loading in SHR resembles that in hypertensive man except that in SHR, a simultaneous kaliuretic response is absent.

Animals↗
PubMed1975

Electrical properties of amphibian urinary bladder epithelia. I. Inverse relationship between potential difference and resistance in tightly mounted preparations.

In an attempt to find a high-resistance epithelium suitable for microelectrode work, we have studied the electrical properties of Necturus and Amphiuma urinary bladders in comparison to toad bladder. Improved mounting techniques were developed, which yield better reproducible degrees of distension and prevent electrical leaks around the edge of the preparation in the Ussing chamber. Transepithelial potential difference and resistance was measured with NaCl Ringer's on either surface of the epithelium, as well as under conditions of ion substitutions and in the presence of amiloride. Compared to data from conventionally mounted toad bladders reported in the literature, our experiments yielded higher potential differences and resistances in all three species. In Necturus values of up to 175 mV and 75 komega cm2 were recorded. Furthermore an inverse relationship was observed between potential difference and resistance, which was not noticed previously with the conventional mounting technique. The relationship is discussed quantitatively in terms of the two-membrane model of active Na+ transport, for which it provides further supportive evidence.

Amiloride↗
PubMed1975

Quantitative relationship of renal glucose and sodium reabsorption during ECF expansion.

To investigate the quantitative relationship between glucose and sodium reabsorption during extracellular fluid (ECF) expansion and to examine the possible contribution to glucosuria of passive diffusion of glucose from peritubular blood to tubular fluid, renal clearance studies were carried out in dogs. It was found that ECF expansion with isotonic saline or Ringer solution causes a decrease in the maximal rate of glucose reabsorption (TmGlc), which is inversely and linearly related to fractional sodium excretion (FENa) over a range from less than 1% more than 25% FENa (r equals -0.394, P less than 0.001). A continuous relationship between TmGlc and FENa could be demonstrated as the ECF was expanded in individual animals as well as in pooled data. Infusion of albumin solution to preferentially expand the plasma volume and decrease proximal tubular sodium reabsorption produced a 24% fall in TmGlc suggesting that the proximal tubule is the site of interrelated glucose and sodium reabsorption. After pulse injections into the renal artery, [14-C]glucose and insulin had the same appearance time in the urine, thus failing to demonstrate diffusion of glucose from blood into the tubule in saline-loaded dogs as well as in dogs in normal sodium balance. It is suggested that ECF expansion exerts its effect on glucose reabsorption by inhibiting the coupled transport of glucose and sodium across the epithelium of the renal proximal tubule.

Albumins↗
PubMed1971

Intestinal transport of water and electrolytes during extracellular volume expansion in dogs.

The effects of extracellular fluid volume expansion on intestinal transport of salts and water were studied in dogs by perfusing loops of bowel in vivo. Saline loading caused depression of duodenal and jejunal absorption with net secretion of salt and water into the lumen. Studies of unidirectional transport of (22)Na(+) revealed that the negative net sodium flux was due primarily, and perhaps exclusively, to increased serosal to mucosal transport, for mucosal to serosal sodium transport was not changed during volume expansion. Net transport of water and potassium paralleled net sodium flux. Administration of deoxycorticosterone did not affect the intestinal response to saline loading. Hemodilution, accomplished by equilibrating the dogs' blood with a reservoir of saline, did not affect intestinal absorption, but isotonic, iso-oncotic expansion of the extracellular fluid produced by reinfusing the saline-blood mixture from the reservoir resulted in negative net transport of water, sodium, and potassium by the duodenum. It is suggested that the small bowel is capable of secreting salts and water through intercellular spaces, and that this process is stimulated by extracellular fluid volume expansion.

Animals↗