Abnormal glomerular and tubular function during angiotensin converting enzyme inhibition in renovascular hypertension evaluated by the lithium clearance method

Glomerular filtration rate (GFR) and tubular function were measured by means of the lithium clearance technique in 14 patients with renovascular hypertension (RVH) and eight patients with essential hypertension (EH) before and after oral administration of captopril 25 mg. In RVH captopril reduced 51-Cr-EDTA clearance (67.3 (median) to 47.5 ml min-1, P less than 0.01), proximal absolute reabsorption of fluid (53.9 to 41.5 ml min-1, P less than 0.01) and distal absolute reabsorption of sodium (2195 to 1402 mumol min-1, P less than 0.01), whereas proximal fractional reabsorption increased slightly (77.5 to 80.2%, P less than 0.02). In EH, however, these parameters were practically unaffected by captopril. In both RVH and EH plasma concentrations of angiotensin II and aldosterone were reduced after captopril, but atrial natriuretic peptide in plasma and urinary excretion rate of prostaglandin E2 were unchanged. Blood pressure decreased after captopril in both groups, but the maximum fall in systolic BP was more pronounced in RVH (22%) than EH (13%). It is concluded that angiotensin converting enzyme inhibition markedly reduced absolute reabsorption in both the proximal and distal tubules in RVH, in contrast to EH, predominantly due to fall in the GFR, and that the slight increase in proximal fractional reabsorption may be attributed to a reduction in the hydrostatic pressure in the peritubular vessels.

Elevated angiotensin II and vasopressin in primary hyperparathyroidism. Angiotensin II infusion studies before and after removal of the parathyroid adenoma

In order to evaluate the role of calcium metabolism in blood pressure regulation, 15 patients with primary hyperparathyroidism and 9 healthy control subjects were studied before and during angiotensin II infusion. The patients were re-investigated 2-5 months after removal of the parathyroid adenoma. Blood pressure, plasma levels of angiotensin II, aldosterone, arginine vasopressin, and atrial natriuretic peptide, and creatinine clearance were determined. Blood pressure and the blood pressure response to angiotensin II infusion were both the same before and after the operation. Angiotensin II and arginine vasopressin during basal conditions were significantly higher before than after the operation (angiotensin II: 17 (median) to 10 pmol/l, P less than 0.02; arginine vasopressin: 2.9 to 1.9 pmol/l, P less than 0.01), whereas aldosterone, atrial natriuretic peptide, and creatinine clearance were unchanged. During angiotensin II infusion, aldosterone, arginine vasopressin, and atrial natriuretic peptide increased to approximately the same levels before and after the operation. Blood pressure was not correlated to any of the hormones measured. Thus, patients with primary hyperparathyroidism have elevated plasma levels of angiotensin II and arginine vasopressin which may be compensatory phenomena counteracting volume depletion owing to a decreased renal concentrating ability induced by hypercalcemia, and owing to PTH-induced inhibition of renal sodium reabsorption.

Enzyme immunoassay of hemoglobin A1c: analytical characteristics and clinical performance for patients with diabetes mellitus, with and without uremia

We evaluated an enzyme immunoassay (Novo BioLabs) for determination of hemoglobin A1c and measured the contribution of carbamylated hemoglobin to the hemoglobin A1c results obtained by HPLC for patients with chronic renal failure. The reference interval, determined for blood donors, was 0.035-0.050 (i.e., 3.5% to 5% of the total hemoglobin). For non-diabetic patients with chronic renal failure, on hemodialysis, the mean proportion of hemoglobin A1c was 0.038 (SD 0.0045); for umbilical cord blood it was 0.006-0.009. For diabetic patients with normal or near-normal renal function, results by enzyme immunoassay (y) and HPLC (x) correlated well (r = 0.83): y = 0.99x - 0.005. Added fetal hemoglobin or carbamylated hemoglobin did not interfere with enzyme immunoassay, but added carbamylated hemoglobin co-chromatographed with hemoglobin A1c. Measurements for patients with chronic renal failure, with or without diabetes, by enzyme immunoassay and by HPLC, were compared with measurements for patients with diabetes mellitus but no renal failure. Carbamylated hemoglobin contributed 0.019 to the hemoglobin A1c results obtained by HPLC for patients with chronic renal failure.

Enzyme immunoassay of hemoglobin A1c: analytical characteristics and clinical performance for patients with diabetes mellitus, with and without uremia

We evaluated an enzyme immunoassay (Novo BioLabs) for determination of hemoglobin A1c and measured the contribution of carbamylated hemoglobin to the hemoglobin A1c results obtained by HPLC for patients with chronic renal failure. The reference interval, determined for blood donors, was 0.035-0.050 (i.e., 3.5% to 5% of the total hemoglobin). For non-diabetic patients with chronic renal failure, on hemodialysis, the mean proportion of hemoglobin A1c was 0.038 (SD 0.0045); for umbilical cord blood it was 0.006-0.009. For diabetic patients with normal or near-normal renal function, results by enzyme immunoassay (y) and HPLC (x) correlated well (r = 0.83): y = 0.99x - 0.005. Added fetal hemoglobin or carbamylated hemoglobin did not interfere with enzyme immunoassay, but added carbamylated hemoglobin co-chromatographed with hemoglobin A1c. Measurements for patients with chronic renal failure, with or without diabetes, by enzyme immunoassay and by HPLC, were compared with measurements for patients with diabetes mellitus but no renal failure. Carbamylated hemoglobin contributed 0.019 to the hemoglobin A1c results obtained by HPLC for patients with chronic renal failure.

Bistability of alpha-motoneurones in the decerebrate cat and in the acute spinal cat after intravenous 5-hydroxytryptophan

1. In the preceding paper (Crone, Hultborn, Kiehn, Mazieres & Wigström, 1988) it was shown that a short-lasting synaptic excitation ('on' stimulus) of extensor motoneurones (primarily triceps surae) in the decerebrate cat often resulted in a maintained excitability increase, which could be reset by a short-lasting inhibitory stimulus train ('off' stimulus). In the present experiments intracellular recording from triceps surae motoneurones and the electroneurogram (ENG activity) from triceps surae nerve branches were performed in parallel. 2. Sustained firing of individual triceps surae motoneurones was most often recorded in parallel with the maintained ENG activity following a synaptic 'on' stimulus. When the motoneurone was silenced, by a hyperpolarizing current through the microelectrode, there was no sign of on-going synaptic excitation during the maintained ENG activity following an 'on' stimulus. It was therefore suggested that voltage-dependent intrinsic properties of the motoneurones themselves could be responsible for the maintained firing. 3. In confirmation of this hypothesis it was found that short-lasting depolarizing current pulses through the recording microelectrode could trigger a self-sustained firing in the motoneurone provided that the bias current (i.e. the holding potential) was kept within certain limits. Hyperpolarizing current pulses terminated the firing. When the spike-generating mechanism was inactivated (by long-lasting excessive depolarization) similar depolarizing and hyperpolarizing current pulses could initiate and terminate plateau potentials in the motoneurones. By grading the depolarizing current pulses it was found that the plateau potentials were of all-or-none character, typically around 10 mV in amplitude. The two levels of excitability which can be triggered by short-lasting excitation and inhibition of the motoneurones is referred to as 'bistable' behaviour of the motoneurones. 4. After an acute spinal transection, in the unanaesthetized cat, the bistable behaviour of the motoneurones disappeared. However, it reappears following intravenous injection of the serotonin precursor 5-hydroxytryptophan (50-120 mg/kg). 5. Individual triceps surae motor units were recorded by selective EMG electrodes during tonic stretch reflexes in the decerebrate preparations. Based on an analysis of their firing pattern during lengthening and shortening (or vibration) of the muscle it is suggested that plateau potentials in motoneurones are recruited during the tonic stretch reflex. Furthermore, it is argued that a quantitatively important part of the depolarization of motoneurones during the tonic stretch reflex indeed originates from these plateau potentials.(ABSTRACT TRUNCATED AT 400 WORDS)

Reduced angiotensin II induced vascular reactivity in chronic renal failure

Eight patients with chronic renal failure before the stage of dialysis (Group 1), 11 patients on regular dialysis treatment (Group 2) and 14 healthy control subjects (Group 3) were studied before, during and after angiotensin II (AII)-infusion. Blood pressure (BP), heart rate (HR), plasma levels of AII, aldosterone (Aldo), arginine vasopressin (AVP), noradrenaline (NA) and adrenaline (A), and serum concentrations of parathyroid hormone (PTH), calcium and magnesium were determined. AII induced vascular reactivity was reduced both in Group 1 and 2 compared with Group 3. Basal AII was the same in the three groups, and only in dialysis patients was AII induced vascular reactivity negatively correlated to basal AII. Aldo and NA were higher in Group 2 than in Group 3, and AVP was higher in both groups of patients compared with controls. HR declined during AII induced elevation of BP in the control subjects but not in the patients. Neither PTH, serum calcium nor serum magnesium was correlated to BP or vascular reactivity. It can be concluded that AII induced vascular reactivity is reduced both in patients with renal failure before dialysis and in patients on regular dialysis treatment. Basal blood levels of Aldo and NA are increased in dialysis patients and AVP is increased in both groups of patients, but neither these abnormalities nor blood levels of PTH, calcium or magnesium seem to be the background upon which the abnormal vascular reactivity develops.

Disturbed relationship between urinary prostaglandin E2 excretion, plasma arginine vasopressin and renal water excretion after oral water loading in early hepatic cirrhosis

An oral water load of 20 ml kg-1 body weight was given to 11 patients with early hepatic cirrhosis and to 16 healthy control subjects. Urinary output (V), free water clearance (CH2O), urinary excretion of prostaglandin E2 (PGE2) and F2 alpha (PGF2 alpha), and plasma concentration of arginine vasopressin (AVP) were determined before and during the first 4 h after loading. During basal conditions, PGE2 excretion was the same in patients (75 pg min-1, median, range 15-569) and controls (78 pg min-1, range 22-262), but during the first hour after water loading, PGE2 increased to a significantly higher level in cirrhotic patients (423 pg min-1, median) than in control subjects (162 pg min-1) (P less than 0.05). No difference in PGF2 alpha excretion was found between the two groups. Urinary output and CH2O were significantly lower after water loading in patients than in controls. Arginine vasopressin before water loading did not differ between patients and control subjects, but after loading it was unchanged in the patients, whereas a significant reduction (1.9 to 1.4 pmol l-1, P less than 0.01) was found in the control subjects. In controls, but not in patients, PGE2 was significantly positively correlated to V and CH2O, and negatively correlated to AVP after water loading. Thus, renal PGE2 excretion is increased and CH2O is decreased after water loading in patients with early hepatic cirrhosis, and a disturbed relationship seems to exist between PGE2 on the one hand, and AVP and renal water excretion, on the other, in these patients after water loading.(ABSTRACT TRUNCATED AT 250 WORDS)

Increased atrial natriuretic peptide in the nephrotic syndrome. Relationship to the renal function and the renin-angiotensin-aldosterone system

Atrial natriuretic peptide (ANP), angiotensin II (Ang II), and aldosterone (Aldo) in plasma and creatinine clearance (Ccr) were determined during basal conditions in 17 patients with the nephrotic syndrome and 20 control subjects. In addition, six of the patients were studied after seven remissions of the syndrome. In the nephrotic syndrome ANP was higher than in the control group (9.7 (median) versus 7.2 pmol/l, p less than 0.01), Ccr was lower (55 versus 99 ml/min, p less than 0.01). Angiotensin II and Aldo were the same in patients and control subjects. After remission of the syndrome ANP was reduced (11.2 to 5.4 pmol/l, n = 7, p less than 0.02) and Ccr increased (52 to 84 ml/min, n = 7, p less than 0.02), whereas Ang II and Aldo were unchanged. A significant, negative correlation was found between ANP and Ccr in the subgroup of patients in whom the syndrome remitted (Q = -0.547, n = 14, p less than 0.05). Atrial natriuretic peptide was not correlated to either Ang II or Aldo in either of the groups. It is concluded that patients with the nephrotic syndrome have elevated ANP, and it is suggested that a high ANP may be a compensatory phenomenon induced by a decreased renal ability to eliminate sodium and water.

Sustained release verapamil in renal hypertension

In 14 patients with arterial hypertension secondary to chronic renal parenchymal disease and impaired renal function, 24-h ambulatory and casual blood pressure readings plasma, angiotensin II, aldosterone, arginine vasopressin and atrial natriuretic peptide, creatinine clearance, plasma lipids and lipoproteins, and body weight were determined after consecutive 3-week periods on placebo and sustained release verapamil 240 mg/day. Verapamil reduced the mean 24-h ambulatory blood pressure from 152/104 to 142/97 mm Hg. Blood pressure was significantly reduced during the daytime and the evening, but not at night. Casual blood pressure was also significantly reduced from 176/106 mm Hg to 154/96 mm Hg. No significant changes were found in the hormones, creatinine clearance, plasma lipids and lipoproteins, heart rate or body weight. The atrial natriuretic peptide level was significantly correlated with the calculated creatinine clearance (r = -0.797). Thus, sustained release verapamil 240 mg as a single daily dose had a moderate hypotensive effect in patients with chronic renal disease without inducing tachycardia, activation of the renin-angiotensin-aldosterone system, or increasing body weight, and without altering renal function and plasma lipids and lipoproteins. The negative correlation between atrial natriuretic peptide and glomerular filtration rate supports the hypothesis that the extracellular volume increases during progression of renal disease.

Malignant arterial hypertension. Relationship between blood pressure control and renal function during long-term observation of patients with malignant nephrosclerosis

Eleven patients with malignant arterial hypertension and malignant nephrosclerosis, verified by percutaneous renal biopsy, were examined during an observation period of 47 months (median). All patients received antihypertensive therapy. Patients were divided into three groups with regard to development of renal function during the observation period. In two patients (group I), the integrated average blood pressure (IA-BP) was 134/95 mmHg (median) and the calculated creatinine clearance (Ccr) increased from 19 to 56 ml/min (medians). In four patients (group II), IA-BP was 154/102 mmHg and Ccr remained stable-at approximately 60 ml/min. In five patients, (group III), IA-BP was 189/114 mmHg, owing to lack of patient compliance and absence from regular control, and Ccr was reduced from 26 ml/min to less than 5 ml/min. During the first 2 months of antihypertensive therapy, renal function was temporarily reduced in 7 of the 11 patients. It is concluded that effective blood pressure control in patients with malignant arterial hypertension and malignant nephrosclerosis can be accompanied by a considerable improvement, or at least a preservation of renal function.

Relationship between urinary prostaglandin E2 and F2 alpha excretion and plasma arginine vasopressin during renal concentrating and diluting tests in renal transplant recipients

Urinary excretion of prostaglandin E2 (PGE2 and F2 alpha (PGF2 alpha) and plasma concentration of arginine vasopressin (AVP) were determined during urinary concentrating and diluting tests in renal transplant recipients and control subjects. During the concentrating test PGE2 and PGF2 alpha remained unchanged in the renal transplant recipients, whereas both PGE2 and PGF2 alpha were significantly reduced in the control subjects. During the diluting test PGE2 and PGF2 alpha increased in both groups but, contrary to PGF2 alpha, PGE2 was significantly higher in all periods in the transplant recipients compared to the controls. However, the prostaglandin excretion rates per kidney were significantly higher in the renal transplant recipients than control subjects, for all periods during both the concentrating and the diluting test. Arginine vasopressin was significantly higher in renal transplant recipients than control subjects during basal conditions, increased to a significantly higher level in the transplant recipients after thirst, but was reduced to the same levels in the two groups during the diluting test. It is concluded that the increased excretion of prostaglandins in renal transplant recipients may be a compensatory phenomenon representing an adaptation to a reduced renal mass in order to maintain adequate renal water excretion. Although a direct relationship between the prostaglandin excretions of PGE2 and PGF2 alpha and AVP does not seem to exist, it is possible that the higher prostaglandin excretion in the renal transplant recipients may be a counterbalancing mechanism to the higher AVP level, which most likely is secondary to a decreased responsiveness to vasopressin of the renal collecting ducts in the transplanted kidney.

Reciprocal Ia inhibition between ankle flexors and extensors in man

1. Reciprocal inhibition between antagonist muscle groups at the ankle has been investigated in sixty healthy subjects. Hoffmann reflexes (H reflexes) in the soleus and tibialis anterior muscles were used to assess changes in reciprocal inhibition evoked by electrical stimulation of antagonist muscle nerves. 2. Inhibition of the soleus H reflex was evoked by a single conditioning stimulus to the common peroneal nerve, and inhibition of the tibialis anterior H reflex was elicited by one conditioning stimulus to the posterior tibial nerve. Symmetrical central connections between the antagonist flexors and extensors were assumed and under this assumption the central delay for the inhibition, in addition to the delay for monosynaptic Ia excitation, was calculated to be about 1 ms. The inhibition was evoked by weak stimuli to the nerves from antagonist muscle groups; the threshold for the inhibition was around 0.6 X threshold for a direct motor response (M-threshold). Furthermore, tendon taps to the Achilles tendon facilitated the soleus H reflex and inhibited the tibialis anterior reflex at short latencies. The short central delay, the low electrical threshold and the.actions of Achilles tendon taps strongly suggest that the early reciprocal inhibition is homologous to the disynaptic Ia inhibition previously studied in animal experiments. 3. With the test soleus H reflex kept at 15-25% of the maximum directly evoked motor response (M-response) and the strength of the conditioning peroneal nerve stimulation kept at 1.0 X M-threshold, the inhibition from the peroneal nerve ranged between 0 and 40% (mean, 14.9%) at rest. 4. Changes in the amount of reciprocal inhibition from the peroneal nerve were studied both during tonic and dynamic dorsi- and plantarflexion. During tonic dorsiflexion there was no significant change of inhibition as compared to rest, while inhibition decreased during tonic plantarflexion. However, during ramp-and-hold dorsiflexion there was a transient increase in reciprocal inhibition of the soleus H reflex. This increase in inhibition from the peroneal nerve could be seen 50 ms prior to the onset of contraction. The increase in inhibition before and at the very beginning of the contraction cannot be due to sensory feed-back during contraction, but must depend on a supraspinal control of the spinal cord. 5. At conditioning-test intervals of 4-6 ms, the inhibition of the soleus H reflex from the peroneal nerve was considerably larger during tonic dorsiflexion than at rest. Thus, tonic dorsiflexion revealed an inhibition with long latency from the peroneal nerve, which was not seen at rest.(ABSTRACT TRUNCATED AT 400 WORDS)

Effect of chronic hypokalaemia on renal concentrating ability and secretion of arginine vasopressin

Two patients with a Bartter-like syndrome, who had been hypokalaemic for 129 and 55 months, and 13 normokalaemic control subjects were investigated during 24 h of water deprivation. The hypokalaemic patients had urine volumes, urine osmolalities, osmolar clearances and tubular capacities for water reabsorption within the normal range. During thirst, plasma-arginine vasopressin increased much more markedly in the patients (3.4 to 11.1 pmol/l and 3.0 to 17.7 pmol/l) than in the control subjects (2.1 pmol/l (median), range 1.0-3.1, to 3.7 pmol/l, range 1.7-6.4). Plasma angiotensin II increased during water deprivation in the patients (33 to 53 pmol/l and 147 to 208 pmol/l) but not in the control subjects (9 pmol/l (median), range 3-15, to 11 pmol/l, range 3-15). Plasma aldosterone was the same in patients and control subjects and did not change in response to thirst. It is suggested that renal concentrating ability can be preserved in patients with chronic potassium depletion by means of a compensatory increase in the secretion of antidiuretic hormone.

Morphological and functional characteristics of isolated resistance vessels in advanced uraemia

In order to obtain direct information on the properties of the resistance vasculature of patients with advanced uraemia, a technique was developed to dissect out small arteries (internal diameter about 165 microns) from biopsies of subcutaneous fat. Such arteries responded in a concentration-dependent manner to noradrenaline and angiotensin II, and the maximal force developed suggested that the vessels were fully viable. Although the biopsies were normally taken during operations under general anaesthesia, biopsies taken under local anaesthesia also appeared to be fully viable, suggesting that this technique may prove useful as a general method for studying the intrinsic vascular properties of humans. Biopsies were taken from 20 patients with uraemia, all of whom were treated with chronic intermittent dialysis, and 11 control subjects; up to three vessels were examined per biopsy. The uraemic state was not associated with changes in vascular morphology, or in vascular reactivity or sensitivity to noradrenaline, angiotensin II, potassium or calcium. However, for the uraemic patients and for the controls there was a positive correlation between mean blood pressure and the ratio of vessel media thickness to lumen diameter, as well as a negative correlation between mean blood pressure and vessel active media stress. The results suggest that uraemia treated with dialysis may not be associated with altered properties of the resistance vasculature. However, it appears that uraemic hypertension is associated with both morphological and functional abnormalities of the resistance vasculature.

Hypotension in end-stage renal disease: effect of postural change, exercise and angiotensin II infusion on blood pressure and plasma concentrations of angiotensin II, aldosterone and arginine vasopressin in hypotensive patients with chronic renal failure treated by dialysis

In 16 dialysis patients, 8 hypotensive and 8 normotensive, and 8 control subjects, blood volumes were studied and angiotensin II (AII), aldosterone (Aldo) and arginine vasopressin (AVP) were measured in the supine position, after standing upright for 5 min and after a standard exercise test. In 8 hypotensive and 7 normotensive dialysis patients and in 7 control subjects, the pressor response to AII infusion was determined. Baseline values for AII, Aldo and AVP were the same in the different groups but with a much wider range in uremic patients. After standing for 5 min. both hypotensive and normotensive dialysis patients were able to maintain blood pressure without a significantly greater increase in heart rate than was seen in controls. Contrary to controls, however, all non-nephrectomized dialysis patients responded with an increase in AII and Aldo after standing for 5 min. In controls, exercise induced a clearcut increase in AII, Aldo and AVP, while no such changes were detectable in either hypotensive or normotensive dialysis patients. No significant differences in blood volumes were detectable between the groups. The pressor response to AII infusion was decreased in both normotensive and hypotensive dialysis patients compared with controls. It can be concluded that circulatory adjustment is abnormal in both hypotensive and normotensive dialysis patients as indicated by extremely high baseline levels of AII in some patients, abnormal response of the renin-angiotensin-aldosterone system and AVP to postural change and exercise and a decreased pressor response to AII infusion. However, neither these abnormalities nor changes in blood volumes can directly account for the chronic hypotension seen in some dialysis patients.

Urinary excretion of albumin and beta-2-microglobulin in hypertensive and normotensive renal transplant recipients during urinary diluting and concentrating tests

Urinary excretion of albumin and beta-2-microglobulin was measured in nine hypertensive and nine normotensive renal transplant recipients and 10 healthy control subjects before and after an oral water load of 20 ml (kg body weight)-1 (study 1) and in eight hypertensive and 11 normotensive renal transplant recipients and 11 healthy control subjects during 24-h water deprivation (study 2). In both studies 1 and 2 urinary albumin excretion was significantly higher (p less than 0.01) in the hypertensive renal transplant recipients that in the normotensive patients and the control subjects (levels before loading; hypertensives: 23.9 micrograms/min (median), range 7.5-58.7; normotensives: 3.4 micrograms/min, range 1.0-49.3; controls: 2.9 micrograms/min, range 1.3-10.3). Urinary albumin excretion was significantly positive correlated to both systolic, diastolic and mean blood pressure (for mean blood pressure: rho = 0.625, n = 18, p less than 0.01) in transplanted patients. Albumin excretion tended to increase after water loading and to decrease during water deprivation in all groups. Beta-2-microglobulin excretion was approximately the same in all groups in both studies 1 and 2 and was not correlated to blood pressure. During a follow-up period of at least 18 months, none of the renal transplant recipients developed signs of chronic graft failure. Increased urinary albumin excretion in hypertensive renal transplant recipients thus appears to be caused by increased glomerular permeability that may be due to glomerular damage induced by arterial hypertension corresponding to the findings in essential hypertension.

Segregation of a t(3;20) translocation through three generations resulting in unbalanced karyotypes in six persons

With the aid of high resolution chromosome banding, a t(3;20) translocation was discovered in a large family with six retarded members. The translocation involved very small terminal segments. The unbalanced products resulting in partial trisomy 20q and monosomy 3p were observed in the retarded subjects. Gene localisation studies of the ADA gene, with a presumed locus on the long arm of chromosome 20, were also carried out and seem to exclude this gene from the distal part of 20q (20q13.1----qter).

Renal water excretion before and after remission of nephrotic syndrome: relationship between free water clearance and kidney function, arginine vasopressin, angiotensin II and aldosterone in plasma before and after oral water loading

An oral water load of 20 ml/kg body wt. was given to eight patients with nephrotic syndrome before and after remission of the syndrome, and to 13 healthy control subjects. Urine volume (D), free water clearance (C water), plasma concentrations of arginine vasopressin (AVP), angiotensin II (ANG II) and aldosterone (Aldo), were determined before and three times during the first 4 h after loading. D and C water increased to a significantly lower level (P less than 0.01) after water loading in patients with nephrotic syndrome than in control subjects, but D and C water were normal after remission of the syndrome. The maximum increase in C water (delta C water max.) was 1.07 ml/min (median) before remission and 7.93 ml/min after, compared with 8.01 ml/min in the control group. Creatinine clearance (Ccr) increased significantly after remission (63 ml/min to 88 ml/min, P less than 0.01), and the fractional excretion of sodium was enhanced. AVP was higher in the nephrotic syndrome both before (2.9 pmol/l) and after remission (2.9 pmol/l) compared with the control group (1.8 pmol/l). ANG II and Aldo did not change after remission and remained at the same level as in the control group. The elevation in delta C water max. after remission was accompanied by an increase in Ccr in all patients and delta C water max. and Ccr were significantly correlated (rho = 0.600, n = 16, P less than 0.05). No relationship was found between the change in delta C water max. and ANG II and Aldo.(ABSTRACT TRUNCATED AT 250 WORDS)

Inherited tandem duplication dup(X) (q131-q212) in a male proband

A tandem duplication dup(X) (q131-q212) has been diagnosed neonatally because of the peculiar appearance. Family investigation demonstrated that the duplication has segregated through phenotypically normal female carriers for at least three generations. Inactivation studies showed that the aberrant X was preferentially late replicating. The difficulties related to prenatal diagnosis of minor X chromosome aberrations in males are discussed.

Reciprocal Ia inhibition from the peroneal nerve to soleus motoneurones with special reference to the size of the test reflex

The aim of the study was to examine the supraspinal control during voluntary movements of the foot in man, of the Ia inhibitory interneurones activated from the anterior tibial muscle and projecting to the soleus alpha-motoneurones. Previous studies have reported an increased inhibition of the soleus alpha-motoneurones by a constant conditioning stimulus to the common peroneal nerve during dorsiflexion of the foot. This was interpreted as a sign of supraspinal facilitation of the Ia inhibitory interneurones. However, these results could not be reproduced in the present study. The contradictory results can probably be explained by some important methodological differences in the use of the H-reflex technique.

Intrinsic membrane properties causing a bistable behaviour of alpha-motoneurones

In decerebrate cats a train of impulses in Ia afferents may lead to a sustained increase in excitability of alpha-motoneurones of homonymous and heteronymous muscles. It was previously suggested that this long-lasting excitability increase reflects a maintained synaptic input to the motoneurones from excitatory interneurones. With intracellular recording from motoneurones we here demonstrate that the sustained increase of alpha-motoneurone activity is due to an all-or-none plateau depolarization. This plateau can be induced by a short train of excitatory synaptic potentials or a brief, intracellularly injected depolarizing current pulse and is terminated by a short train of inhibitory synaptic potentials or a hyperpolarizing current pulse. It is concluded that maintained motor unit firing triggered by a brief train of impulses in Ia afferent reflects an intrinsic bistable behaviour of alpha-motoneurones.