James W. Culbertson

Nature of the renal concentrating defect in sickle cell disease.

Free water reabsorption (T(c) (H2O)) measured during 10% mannitol diuresis and subsequently during 3% saline diuresis was compared in patients with sickle cell anemia and in normal subjects. During mannitol infusion, T(c) (H2O) progressively rose with increasing osmolar clearance (C(osm)) and reached a maximal level in both groups studied. During hypertonic saline diuresis, T(c) (H2O) progressively rose in the normal subjects and exceeded the maximal levels attained during mannitol diuresis, with no evidence of a maximal T(c) (H2O) level appearing. In contrast, none of the saline curves significantly exceeded the mannitol curves in the sickle cell patients but tended to parallel the mannitol curves at comparable rates of solute clearance. Since T(c) (H2O) is an index of both solute (sodium) transport from the loop of Henle and solute accumulation in the hypertonic medullary interstitium, tubular sodium handling was examined in both sickle cell patients and control subjects alike. No difference in the tubular transport of sodium could be demonstrated either under conditions of sodium loading or under conditions in which the tubular sodium load was low (water diuresis). These data support the conclusion that the defect in urinary concentration in sickle cell patients is caused by a limitation in maintaining a high concentration of solute in the medullary interstitium, thus limiting the rate of T(c) (H2O) from the collecting duct.

THE EFFECT OF SPLANCHNIC SYMPATHECTOMY IN HYPERTENSIVE PATIENTS UPON ESTIMATED HEPATIC BLOOD FLOW IN THE UPRIGHT AS CONTRASTED WITH THE HORIZONTAL POSITION

It has been found that when normotensive or hypertensive subjects are tilted passively into an upright position estimated hepatic blood flow (EHBF) (2) decreases and calculated hepatic portal resistance (HPR) increases (3). These changes were assumed to be due to active splanchnic vasoconstriction, probably mediated over the splanchnic sympathetic nervous system. Direct evidence bearing on this assumption became available in some of the hypertensive patients undergoing splanchnic sympathectomy and subsequently studied by the same methods as before operation. Such studies are the basis of the present report.

Catheterization of the coronary sinus in man.

Abstract An intravenous catheter was introduced inadvertently into the coronary sinuses of four patients in the course of a series of twenty-five cardiac catheterization studies (a frequency of 16 per cent). Samples of coronary venous blood were taken for oxygen analysis, and pressure tracings were obtained with a Hamilton manometer. These cases are reported and criteria for identifying this catheter position are presented. Oxyhemoglobin saturation values were found to be strikingly low (average, 30 per cent in four cases) as compared with control values for mixed venous blood (average, 73 per cent in fifty subjects). Coronary venous pressure levels (0 to 15 mm. Hg) and wave patterns are described. Physiologic implications of the findings and potential applications of the technique are cited.