No abstract

A double-blind crossover study was conducted to evaluate the antitussive effectiveness of diphenhydramine (DPH) in chornic coughs related to bronchitis, at doses of 25 and 50 mg every 4 hr for four doses. Both 25- and 50-mg doses caused a statistically and clinically significant reduction in frequency of coughs, compared to placebo. The most frequently reported side effect was drowsiness, principally at the 50-mg dose level. There was little or no apparent correlation between antitussive effectiveness and incidence of drowsiness, however, suggesting that the two effects were pharmacologically unrelated.

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. 138 Xe 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. KEY WORDSmicrospheres 133 xe washout carotid sinus reflex sympathetic nerves redistribution of intrarenal blood flow renal medullary blood flow renal cortical blood flow

labeled red cells mid I 131 huniiin serum iilbumin were injected intrnvenously into S mongrel dogs. After 1 hour kidneys were removed and frozen rapidly with dry ice. Sections of outer cortex, inner cortex, outer medulla, inner niedulhi, outer pnpilln nnd inner papilla were removed and analyzed for Cr 111 and I 181 radioactivity. Tissue mdioactivity was compared with that of arterial blond and concentrations of labeled red cells and albumin were calculated. No significant difference was found in relative red cell and albumin content between outer and inner cortex. The magnitude of the I 131 albumin content in the cortex Ls interpreted to indicate a sizeable exlruvusvukir exchangeable albumin pool. The renal papillae were extraordinarily deficient in red cells, but contained per ]00 Gin., albumin equivalent to that of 39 ml. of plasma. SKI C!n nlnlion Rrwarrh, Va/ttmr VI. Xorrmbtr at University

No abstract

The renal hemodynamic effects of hypertonic mannitol infusions have recently become of interest. Infusions of this 6 carbon sugar alcohol appear to have the property of preventing postoperative oliguria ( 1 ) and acute tubular necrosis in cases of crossclamping of the abdominal aorta( 2,3). Experimentally, these infusions have resulted in increased total renal blood flow in hypotensive(4,S) and normotensive(6) dogs as measured by clearance techniques, and in medullary blood flow in normotensive animals as determined by decreased dye transit time ( 7).It has been suggested (7,8,9) that mannitol infusions act by decreasing renal vascular resistance. The present study was undertaken in an attempt to determine the mechanism whereby hypertonic mannitol exerts its effect on renal vascular resistance in the in situ perfused kidney preparation.Methods. Ninety-three studies were carried out in 34 mongrel dogs (10.5-16.4 mg/ kg) of both sexes. After intravenous pentobarbital anesthesia (25 mg/kg) and positive pressure endotracheal respiration with room air were established, the left kidney was exposed through a flank incision.This kidney was perfused in situ (Fig. 1) by means of plastic tubing passing from the left carotid artery through a Sigmamotor pump into the abdominal aorta. The distal * Supported in part by grants H2987 and HE5527 from Nat. Heart Inst., U.S.P.H.S. t U.S.P.H.S. Specid Fellow HSP-17,949.part of this system was a plastic cannula tied into the aorta 2 cm below the left renal artery. The aorta was occluded just above the left kidney by means of a Potts clamp, and all lumbar vessels in the area were ligated. The only tissue perfused by this system was the left kidney. Since this pump was capable of supplying a constant flow against variations in resistance pressure from 0 to 400 mm Hg, any changes in renal vascular resistance were directly reflected in changes in pressure in the circuit. Flows were adjusted to maintain renal perfusion pressure close to control arterial blood pressure. During measurements of changes in renal vascular resistance, flow rates were not changed from control values. Pressures were measured in the brachial artery and in the perfusion tubing at a point between the Sigmamotor pump and the site of aortic cannulation. The latter pressure was taken as equivalent to renal artery pressure. Renal vascular resistance was calculated as the mean renal artery pressure (mm Hg) divided by pump flow (ml/min).Isolation of the perfusion system was confirmed in each experiment by momentarily (1-3 seconds) turning the Sigmamotor pump off and observing the fall in renal artery pressure to approximately 5 mm Hg.By means of an infusion pump, mannitol was infused directly into the renal artery as a 6.6% solution in distilled water at a rate of 1.9 ml/min.

The accumulation of intra-arterially injected I 131 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.

The effectiveness of an interactive multimedia computer program, the "Electronic Textbook in Human Physiology," in improving the knowledge of students studying cardiovascular physiology was determined from scores on tests given before and immediately after completion of a two-hour animation program on the Cardiac Cycle and Introduction to Electrocardiography and by comparison of performance on a final examination taken later with their unexposed (control) classmates. Unsigned comments on the use of the program were obtained from all participants and were universally laudatory. A marked and significant improvement in the immediate posttest compared with the pretest scores was found. More importantly, the students who had used the computer program achieved a significantly higher grade in the cardiovascular section of the final exam than their (control) classmates. Several possible explanations of the results are offered; the most likely one is that the use of the computer program facilitated learning. The implications of this, especially for curriculum planning, are discussed.