Lawrence S. Lilienfield

Intrarenal Blood Flow Distribution in Canine Puppies

Extract: The present study was designed to examine the developmental changes in renal blood flow distribution in canine puppies utilizing the techniques of xenon-133 (133Xe) washout, anatomic measurements, and para-aminohippuric acid (PAH) clearances and extractions. The distribution patterns determined by analysis of the xenon washout curves were confirmed by studies of the intrarenal distribution of injected radioactive microspheres. The mean total blood flow was 1.2 ml/g kidney/min at 6 weeks of age and rose progressively to the adult value of 3.5 ml/g kidney/min at 14–16 weeks of age. The mean Component I flow, 1.7 ml/g/min at 6 weeks, increased to 4.7 ml/g/min at 14–16 weeks of age. The increase in Component I flow was associated with an increase in PAH extraction ratio. The low renal blood flow observed in the puppy less than 6 weeks of age appears to be due in large part to a small cortical volume. Anatomically, the amount of cortex/medulla ratio was less in the puppy than in the adult, and this was supported by the relatively low cortical volume of distribution noted in the washout studies. At 10 and 12 weeks of age, when the relative cortical mass approximated that found in the adult, the Component I flow rate was still low, but from age 12 weeks, Component I flow and total renal blood flow increased markedly. Renal blood flow increased during a period when cardiac output per kilogram body weight was constant and total peripheral resistance was rising.The progressive age-dependent increase that was noted in total renal blood flow was primarily due to an increase in cortical flow. The increased cortical flow was in part a consequence of cortical growth; change in sympathetic tone may also have contributed.

Blood Flow in the Renal Medulla

The accumulation of intra-arterially injected I131 albumin in the papilla of the kidney was measured in a series of 33 anesthetized dogs producing hypertonic urine. Although the data were widely scattered, an estimate of the average rate of this accumulation during the first half-minute following the start of the infusion was made. From the data, the plasma perfusion rate in the papilla under the experimental conditions was calculated and appears to average 25 ml./100 Gm./min.

A Clinical Appraisal of Pentapyrrolidinium (M&B 2050) in Hypertensive Patients

The new ganglionic blocking agent, pentapyrrolidinium or M&B 2050, appears to have several distinct advantages over hexamethonium in the treatment of severe hypertension. These advantages include longer duration of action, greater potency, less tolerance, less interference with intestinal motility, and, most important, a more uniform response from day to day on oral administration. However, critical adjustment of dosage is necessary and side effects are not infrequent, the most disturbing being postural faintness and impotence.

TRANSCAPILLARY MIGRATION OF HEAVY WATER AND THIOCYANATE ION IN THE PULMONARY CIRCULATION OF NORMAL SUBJECTS AND PATIENTS WITH CONGESTIVE HEART FAILURE

During recent years numerous investigations have been concerned with the rates of transfer or exchange of various substances across capillary beds (1-6). These studies, by analyzing curves of disappearance over several minutes from arterial plasma of intravenously injected tracer substances, have provided some information relative to all capillary beds combined. However, this type of experiment has not permitted a close analysis of the behavior of a substance during its first passage through a single organ capillary bed. Recently developed techniques (7-9) now permit the clinical investigator to examine the phenomena of transcapillary exchange of water and other diffusible substances in local vascular areas. This study was undertaken in an attempt to determine in vivo the diffusion characteristics of the pulmonary capillary bed in man with regard to deuterium oxide and an electrolyte, thiocyanate ion. Seven normal subjects and seven patients with pulmonary congestion due to heart failure were studied. The resulting data relating to the pulmonary capillaries were then compared to those previously obtained using similar tracer substances in the capillaries of the human forearm (7).

Intracortical Distribution of Renal Blood Flow in Hemorrhagic Shock in Dogs

The effect of acute hypotensive hemorrhage on the intracortical distribution of renal blood flow was studied in anesthetized mongrel dogs with radioactive microspheres. In the early stages of shock, when carotid artery manipulation was avoided, outer cortical blood flow fell drastically and juxtamedullary flow was relatively well preserved. Carotid artery cannulation caused a redistribution of blood flow within the kidney even before hemorrhage, presumably by stimulating the carotid sinus reflex. Subsequently, with hemorrhage there was a parallel reduction in outer cortical and juxtamedullary blood flow. 138Xe washout curves agreed with the microsphere findings. It was concluded that when the carotid artery was not disturbed, juxtamedullary blood flow was selectively preserved in the early stages of acute hypotensive hemorrhage.

Glomerular Filtration during Stop-Flow

Summary The ganglion stimulating properties of histamine and McN-A-343 were used to investigate whether the superior cervical ganglion becomes supersensitive to drugs following chronic denervation. Nictitating membrane contractions were used to measure ganglionic stimulation. The results strongly indicate that the chronically denervated superior cervical ganglion does not become supersensitive to either histamine or McN-A-343. The increased response of the chronically decentralized nictitating membrane following ganglionic stimulation by the two agents can be completely accounted for by an increased sensitivity of the membrane to relased postganglionic norepinephrine. It is suggested that the classical law of denervation supersensitivity of Cannon and Rosenblueth does not pertain to the superior cervical ganglion.

The Role of the Autonomic Nervous System in Intrarenal Regulation of Renin Secretion

Since the isolation of angiotensin from dog plasma 30 years ago, investigators have devoted considerable effort to elucidating the mechanism of regulation of renin secretion. Initially, attention was directed at the role of renal arterial pressure, or pulse pressure as the regulating factor. However, more recent studies, using a refined technique for measuring renin activity, demonstrate that renin secretion can vary quite independently of arterial (1) or pulse pressure changes (2). A number of reports appear to stress the role of the autonomic nervous system (1, 3-5), body sodium or volume changes (6, 7), and intrarenal mechanisms unrelated to blood pressure changes. Because of their anatomical and functional relation to the renin secreting cells of the juxtaglomerular apparatus, the macula densa cells of the distal tubule have been considered to be involved in the intrarenal regulation of renin secretion (8-11). The sodium concentration of the tubular fluid or sodium reabsorption at this site may in some way affect renin release. Part I of the present study was designed to examine the role of this intrarenal mechanism, namely, to see the effect of changing distal sodium reabsorption on renin secretion. It was found that the saluresis brought on by administration of chlorothiazide in the dog resulted within 15 min in an increased secretion of renin even when urinary loss of water and salt was replaced. Part II therefore was undertaken to see whether this same effect of chlorothiazide obtained in man and whether this effect was under the influence of the autonomic nervous system. The effect of the diuretic on peripheral renin activity was measured before and after neuronal depletion of catecholamines induced by chronic reserpine administration. Part I. Methods. This study was carried out in 10 mongrel dogs, weighing between 10 and 15 kg.

UNRWA and the Health of Palestinian Refugees

Abstract The United Nations Relief and Works Agency for Palestine refugees (UNRWA) has provided health, education, and welfare services since 1949. A team of physicians from Georgetown University visited UNRWA Health Centers and refugee camps in Jordan, Lebanon, the West Bank, and the Gaza Strip, as well as some affiliated hospitals. Living conditions of refugees vary widely. In Jordan and the West Bank, fewer than one third live in camps, whereas in the Gaza Strip and Lebanon, conditions are more crowded. Effective programs for health education, maternal and child health, and immunization have markedly improved the health of the refugees over the years of UNRWAs operation. The general health of the population is good, primarily as a result of wise emphasis on public health and preventive medicine measures.

UNRWA and the health of Palestinian refugees. United Nations Relief and Works Agency.

The United Nations Relief and Works Agency for Palestine refugees (UNRWA) has provided health, education, and welfare services since 1949. A team of physicians from Georgetown University visited UNRWA Health Centers and refugee camps in Jordan, Lebanon, the West Bank, and the Gaza Strip, as well as some affiliated hospitals. Living conditions of refugees vary widely. In Jordan and the West Bank, fewer than one third live in camps, whereas in the Gaza Strip and Lebanon, conditions are more crowded. Effective programs for health education, maternal and child health, and immunization have markedly improved the health of the refugees over the years of UNRWAs operation. The general health of the population is good, primarily as a result of wise emphasis on public health and preventive medicine measures.

Demonstration of Countercurrent Diffusion Exchange in the Vasa Recta of the Renal Medulla.

Summary The accumulations of Rb86 and I131 albumin were compared in the cortex, outer medulla and papilla of 6 hydro-penic anesthetized mongrel dogs. Only one-half as much rubidium as albumin appeared in the papilla in 20 seconds of perfusion, while almost twice as much appeared in the outer medulla and 5 times as much in the cortex. In 3 hydropenic dogs perfused with Na22Cl and I131 albumin the Na22+ was similarly excluded from the papilla. These data suggest that the vasa recta do indeed function as countercurrent exchangers to maintain the high renal medullary solute concentrations and gradient, necessary to conserve body water. The authors gratefully acknowledge the technical assistance of Mrs. Jean B. Young and Mr. Thomas F. Doyle.