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R J Viskoper

Publications and source records attributed to R J Viskoper.

35 records · Page 2Linked to original sources
PubMed1977

Renin stimulation by isoproterenol and theophylline in the isolated perfused kidney.

The intrarenal mechanisms of renin release were studied in the isolated perfused rabbit kidney during stimulation by isoproterenol, 0.01 mug/kg per min, and by theophylline, 0.87 mg/kg per min. In the absence of urinary flow during the early stages of perfusion, isoproterenol caused a 17% increase of renal vein serum renin concentration (RVSRC) (P less than 0.001) without changing renal blood flow, renal vascular resistance, or serum potassium. dl-Propranolol, 2.0 mg/kg per min. abolished this isoproterenol-induced renin release. A moderate reduction in perfusion pressure prior to the infusion of isoproterenol resulted in a marked additional stimulation of renin release. Studies during and following ureteral occlusion demonstrated that theophylline stimulates renin release by decreasing renal vascular resistance, whereas the concomitant increase in sodium transport to the macula densa exerted an opposite effect. dl-Propranolol did not affect theophylline-induced renin secretion. It is concluded that single exogenous stimuli may activate more than one intrarenal mechanism simultaneously. Isoproterenol has a direct renin-stimulatory effect on intrarenal beta-adrenergic receptors that may be reinforced by baroreceptor stimulation. Theophylline stimulates renin via a baroreceptor mechanism, with simultaneous renin suppression via a sodium-macula densa effect.

Animals↗
PubMed1977

Mechanisms of hypertension during the acute and intermediate phases of the one-clip, two-kidney model in the dog.

The acute and intermediate onset phases of one-clip, two-kidney hypertension were studied in six conscious dogs. Mean arterial pressure (MAP), cardiac output (CO), total peripheral resistance (TPR), serum renin concentration (SRC), plasma aldosterone (PA) and cumulative sodium and water balance were studied prior to unilateral renal artery constriction, at 2, 10, and 24 hours postconstriction, and daily thereafter for 5 days. At 2 hours postconstriction, MAP, CO, TPR, and SRC were elevated, with unchanged fluid balance. At 10 and 24 hours there was a further rise in CO accompanied by positive fluid-sodium balance, with a slight decrease in MAP, TRP, and SRC. During days 2 and 3, MAP, CO, TPR, and SRC remained elevated and stable in the presence of decreasing fluid-sodium balance to preconstriction levels. During days 4 and 5, MAP, SRC, and fluid-sodium balance remained unchanged, TPR demonstrated a secondary increase, whereas CO decreased to preconstriction values. Sequential changes in PA parallel those of SRC, but were significant only at 2 hours postconstriction. These changes suggest that the increased CO is not totally dependent on fluid-sodium balance, and that CO is not the sole determinant of elevated MAP. The temporal relationship between MAP and SRC throughout the study is consistent with renin-mediated hypertension. The secondary rise of TPR may be due to total body autoregulation and/or increased vascular reactivity to high levels of circulating angiotensin. A unitary renin-angiotensin mechanism, therefore, may be responsible for the induction and maintenance of hypertension in this experimental model.

Acute Disease↗
PubMed1975

Bilateral slipped upper femoral epiphysis: a rare manifestation of renal osteodystrophy. Case report with discussion of its pathogenesis.

Bilateral slipped upper femoral epiphysis is a rare manifestation of renal osteodystrophy. A case of bilateral slipped femoral epiphysis in an 18-year old male suffering from chronic renal failure due to oligomeganephronic renal hypoplasia with profound signs of renal osteodystrophy is presented. Serum growth hormone levels were high, while those of urinary 17-ketosteroids were decreased. Following subtotal parathyroidectomy, the progression of the process leading to slipped epiphysis was halted with closure of the epiphyses. The patient was subsequently treated with chronic hemodialysis for several months, after which successful renal transplantation was performed. The pathogenesis of renal osteodystrophy leading to slipped epiphysis is discussed and attention drawn to the fact that bilateral slipped femoral epiphysis may be the first clinical sign of chronic renal insufficiency.

17-Ketosteroids↗
PubMedDate not supplied

McArdle's syndrome: the reaction to a fat-rich diet.

The effect of a diet enriched with fats on the muscle performance of a patient with McArdle's syndrome was studied. The tolerance to physical activity was studied during exercise (ergometric examination) and by sustained abduction to 90 degrees of the deltoid muscle, both after a three-day period on a normal diet and after a three-day period on a fat-rich diet. After the first period a woody spasm of the deltoid muscle was found which lasted several days. After a period on fat-rich diet the patient's physical fitness was increased and the recovery period after the acute load was shorter. Moreover, no induration of the deltoid muscle was observed after the sustained abduction to 90 degrees. It is argued that maximal strength is not improved by a fat-rich diet but tolerance to submaximal loads is increased by such treatment and recovery from non-lactate-produced muscle discomfort is hastened.

Adult↗