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Biomedical subjects

C Swartz

Publications and source records attributed to C Swartz.

At least 19 recordsLinked to original sources
PubMed1979

Neurogenic activity--angiotensin II interaction during the development and maintenance of renal hypertension in the rat.

1. Pentolinium tartrate (a ganglionic blocker) was injected in conscious rats during the early and late phases of two-kidney renal hypertension produced by aortic ligation. 2. In the early phase ( 5 days after aortic ligation), ganglionic blockade resulted in a decrease in blood pressure equal to that obtained in normotensive rats. Later, at days 12 and 40, for equally severe hypertension, ganglion blockade resulted in a greater decrease in blood pressure. 3. A 30 min infusion of [Sar1, Ala8]angiotensin II during the pentolinium-induced nadir in blood pressure resulted in a further decrease in blood pressure at day 5. Later, at days 12 and 40, this effect was smaller. 4. A 300 min infusion of [Sar1, Ala8]angiotensin II normalized the blood pressure in hypertensive rats at day 40. This delay response may be secondary to a central effect of the antagonist, reducing neurogenic tone or peripheral antagonism of locally generated angiotensin II in the blood vessel walls. 5. At day 40, removal of the small left kidney resulted in a greater decrease in blood pressure. This suggests the presence of a renal factor other than renin in the chronic phase of this hypertension.

Angiotensin II↗
PubMed1979

Clinically occult diffuse proliferative lupus nephritis. An age-related phenomenon.

Thirteen patients with systemic lupus erythematosus (SLE) who had normal results of urinalysis, absence of proteinuria, and normal serum creatinine values underwent renal biopsy. Three of 13 patients had diffuse proliferative glomerulonephritis (group 1). Biopsy specimens showed segmental fibrinoid necrosis, diffuse mesangial hypercellularity, and substantial immunoglobulin deposition. Group 2 comprised those patients whose histologic findings did not portend a poor prognosis. Four had mesangial proliferative glomerulonephritis, three had focal proliferative glomerulonephritis, and three had minimal mesangial widening. The values of inulin clearance in group 1 did not differ significantly from those in group 2. Patients in group 1 had a mean age of 19 years, a value significantly lower than in group 2 (41.8 years). Review of previous reports also supports the thesis that this phenomenon is age related. Our study underscores the importance of renal biopsy in patients with SLE despite the absence of clinical evidence of renal involvement, particularly in patients under 30 years of age.

Adult↗
PubMed1979

Glomerular lesions in benign essential hypertension. A study of eight biopsy specimens with laboratory evidence suggestive of glomerular abnormalities.

We performed renal biopsies on eight patients who had benign essential hypertension but laboratory abnormalities suggestive of glomerulonephritis. Persistent microscopic hematuria was detected in four patients, proteinuria in five, RBC casts in two, and decreased glomerular filtration in seven. In all eight biopsy specimens, we detected hyaline arterionephrosclerosis, focal glomerular obsolescence, and segmental, afibrillar thickening of glomerular basement membranes. Direct immunofluorescence studies performed on all eight samples were negative for immunoglobulins, complement, and fibrinogen. Although the patients in our study had laboratory findings suggestive of glomerulonephritis, the morphologic changes were indicative of benign essential hypertension.

Adult↗
PubMed1978

Long-term clinical effects, bioavailability, and kinetics of minoxidil in relation to renal function.

Minoxidil was used to treat 26 patients (17 to 67 years old) with severe hypertension and varying degrees of renal function. Our object was to assess long-term clinical efficacy, kinetics (acute and chronic), and bioavailability of minoxidil in chronic renal insufficiency. Minoxidil, 27 to 30 mg per day, decreased systolic and diastolic blood pressure during the first three months of therapy. Between the third and 24th months (30 months in one patient) there was no further change. Propranolol or clonidine was needed to control heart rate, and furosemide or dialysis was needed to control edema induced by minoxidil. Renal function improved in some of the mildy azotemic patients. Minoxidil kinetics after the customary dose did not differ whether the drug was taken as tablet or solution. Kinetic parameters during chronic administration of minoxidil did not differ from those after acute administration. The kinetics in chronic renal insufficiency do not differ from these in subjects with normal renal function.

Adolescent↗
PubMed1978

Effect of administration of Sar1-Ala8-angiotensin II during the development and maintenance of renal hypertension in the rat.

1. Sar1-Ala8-Angiotensin II (an angiotensin antagonist) was infused in rats during the development and maintenance of renal hypertension produced by aortic ligation between renal arteries. 2. In the early phase (5 and 12 days after ligation), infusion of the antagonist markedly decreased blood pressure although it did not reach normal pressures. Later (day 40) only a modest decrease in blood pressure was noted. 3. Removal of the small left kidney always decreased the blood pressure to normal pressures. 4. It is concluded that the renin-angiotensin system is the major pressor component in the initiation of this hypertension. Later, other factors of renal origin assume a pressor function.

Angiotensin II↗
PubMed1977

Effect of propranolol on blood pressure and renin in renal hypertension in the rat.

1. Propranolol was administered to groups of mature rats before and during the development of renal hypertension induced by ligation of the aorta between the renal arteries. 2. At a dose 10 mumol (3 mg) of propranolol/kg, administered by intraperitoneal injection, the onset and severity of hypertension were not affected, although plasma renin concentration was significantly lower than in the untreated hypertensive rats in the first 5 days after the operation. 3. With 200 mumol (60 mg) of propranolol/kg, administered in the drinking water, peak blood pressure 5 days after aortic ligation was lower than in the untreated control rats, but plasma renin concentration was no lower than with the smaller dose. 4. The development of severe hypertension despite reduction in plasma renin concentration on the low dose of propranolol suggests the participation of renal vasopressor factors other than renin in this model. 5. A higher dose of propranolol reduced the rise in plasma concentration to an equal extent but the rise of blood pressure at 5 days was also reduced, which supports this concept.

Animals↗
PubMed1976

Salt, frusemide and renin in severe experimental renal hypertension.

1. Sodium-deficient diet failed to alter development and maintenance of severe renal hypertension produced in the rat by ligation of the aorta between the renal arteries. 2. High sodium diet did not alter the early phase of this hypertension, but significantly decreased blood pressure elevation in the late phases. 3. The decrease in blood pressure produced by high sodium intake does not appear to be mediated by renin suppression. 4. Frusemide effectively reduced blood pressure and renin at all phases.

Animals↗
PubMed1976

The haemodynamic response to salt and water loading in patients with end-stage renal disease and anephric man.

1. Patients with end-stage renal disease and anephric patients underwent expansion and depletion of body fluids with salt and water. This resulted in four different sequential haemodynamic patterns: (i) no significant increase in blood pressure; (ii) increase in blood pressure associated with a rise in cardiac output and no effect on total peripheral resistance; (iii) increase in cardiac output followed by a rise in blood pressure and total peripheral resistance; (iv) increase in total peripheral resistance and blood pressure without significant changes in cardiac output. 2. It is concluded that an initial rise in cardiac output is not necessary to increase-blood pressure in either anephric man or patients with end-stage renaldisease.

Blood Pressure↗
PubMed1976

The interrelation of renin and iron binding capacity.

When rats are subjected to hypoxia, an increase in serum angiotensinogen concentration occurs which is accompanied by the appearance of serum erythropoietin (EP) during the first 24 h. Subsequent increases in EP reach maximum values 24 to 48 h after increases in packed cell volume (PCV) and serum renin levels. The current experiments were designed to determine if a decrease in iron stores is the stimulus for renin production when rats are rapidly expanding their red cell volume in a hypoxic environment. Young rats fed McCall's low iron diet were paired with rats fed the same diet supplemented with ferric citrate (6 g/kg diet). After two weeks at ambient pressure, they were subjected to hypoxia (0.48 atm) for 1 to 10 days. After 5 days at the reduced pressure, a fraction of the rats on the low iron diet were fed the iron-supplemented diet. At the time of sacrifice, serum was assayed for total iron binding capacity (TIBC) and renin. Rats that were fed the low iron diet showed an increase in TIBC, an increase in serum renin and a positive correlation between serum renin and TIBC. Rats that were fed a normal iron diet under the same conditions had lower TIBC, lower serum renin and no correlation between serum renin and TIBC. When low iron diet rats were supplemented with iron, TIBC and serum renin decreased. These experiments may have a clinical counterpart. The total iron binding capacity, renin and angiotensinogen were measured in the serum of women during the first 19 weeks of pregnancy. Women during early pregnancy showed an increase in TIBC, an increase of renin and angiotensinogen in the serum and a positive correlation between TIBC and renin concentration. It is suggested that the increased concentration of renin in the serum of women during the first 19 weeks of pregnancy and in the serum of rats that are rapidly expanding their red cell volume are related to a decrease in iron stores.

Angiotensinogen↗
PubMed1976

Experimental model of severe renal hypertension.

A simple technique is described for producing severe reproducible renal hypertension in the rat. Total ligation of the aorta between the renal arteries and just below the origin of the superior mesenteric artery resulted in sustained systolic and diastolic pressures in 90 per cent of 170 rats studied. Arterial pressure is then measured in the conscious unrestrained rat through a carotid cannula inserted no more than 48 hours before measurements are made. The mean arterial pressure increases to a peak of 180 mm. Hg at day 5 and then remains at a plateau of 160 mm. Hg through the 40 days of the study. Plasma renin increases to a peak at 5 days but returns to baseline at 30 days despite the persistence of severe hypertension. Infarction of the left kidney below the aortic constriction results in no increase in pressure or plasma renin. Infarctions of the right kidney by emboli originating from the indwelling carotid cannula are associated with greater increases in blood pressure and plasma renin than the standard preparation. Prolonged carotid cannulation must be avoided in order to prevent such emboli. This simple technique for producing renal hypertension allows studies on the pathogenesis of hypertension with an excellent degree of reproducibility and reliability.

Animals↗
PubMed1975

Cardiac effect of diuretic drugs.

Triamterene, amiloride, ethacrynic acid, and furosemide were studied to determine whether they modified the digitalis-induced egress of myocardial potassium which is thought to facilitate the development of digitalis arrhythmias. In a control group of 15 dogs, potassium was measured in samples obtained simultaneously from the femoral artery (FA) and the coronary sinus (CS) in a control period and at intervals after the administration of 1 mg. of acetylstrophanthidin. Acetylstrophanthidin caused a significant increase in cardiac A-V difference in the potassium concentration (CS-FA) averaging 0.47 mEq. per liter. In a group of 10 dogs, when 175 mg. of triamterene was infused prior to the acetylstrophanthidin, the rise in A-V differnece was abolished and the arrhythmias often aborted. In contrast, the infusion of potent diuretics (40 mg. of furosemide in five dogs and 100 mg. of ethacrynic acid in another five dogs) prior to acetylstrophanthidin, caused a doubling of the maximal A-V potassium difference. This study suggests that the clinical administration of antikaliuretic drugs may prevent the arrhythmias of digitalis toxicity not only by reducing kaliuresis and subsequent hypokalemia, but by a myocardial effect which antagonized the digitalis-induced loss of myocardial potassium. Contrariwise, potent diuretics may facilitate digitalis arrhythmias through a myocardial action causing a greater egress of myocardial potassium, thus explaining the development of arrhythmias despite normal serum potassium levels. These potent diuretics should be used cautiously, especially when given intravenously to patients receiving digitalis.

Amiloride↗