Alfred Blalock

Effects on Blood Pressure of Injection of Kidney Extracts of Dogs with Renal Hypertension

A rise in blood pressure may be produced in dogs either by partial obstruction of the renal arteries 1 or by ligation of the ureters. 2 Since the latter procedure often causes a marked decline in the renal blood flow, 3 it seems likely that the hypertension is in both instances related in some way to ischemia of the kidneys. It was shown by Tigerstedt and Bergman 4 that saline extracts of the kidney of rabbits produced a sustained rise in blood pressure when injected into other rabbits. The object of our experiments was to determine whether extracts prepared from ischemic kidneys, removed from dogs with hypertension, had a greater pressor effect than similar extracts of normal kidneys. The freshly removed kidneys were chopped up with scissors and ground with carborundum and 0.9% salt solution. The suspension so obtained was centrifuged and the supernatant fluid was kept in the ice box until used. Amounts corresponding to 5 gm. of kidney tissue were administered intravenously to normal unanesthetized dogs. Changes in blood pressure were measured by the cuff described by Ferris and Hynes, 5 the passage of the pulse wave being determined by palpation of the dorsal artery of the foot. 6 The results which have been obtained are summarized in Table I. Extracts of the normal kidneys frequently caused a marked preliminary decline in blood pressure, followed in a few minutes by a gradual rise which persisted for 30 minutes or longer. The degree of rise varied from zero to 60 mm. of mercury above the control values. Extracts of the kidneys of dogs with renal hypertension usually caused less preliminary decline and a more marked secondary rise in blood pressure.

Experimental Reversal of Capillary Blood Flow

Beck, Sciaroni and others have made clinical and experimental attempts to reverse the direction of flow of blood across the capillary bed by the anastomosis of arteries and veins. The present authors have shown by the microscopic observation of capillaries in acute experiments on cats, dogs and rabbits that a reversal of blood flow in mesenteric capillaries will occur following the connection of an artery to a vein provided the collateral arteries and veins are obstructed. Furthermore, it was shown that blood flowing in a reverse direction through capillaries loses oxygen.

The Effect of the Pulse upon the Flow of Lymph.

Summary Pulsations in lymphatics synchronous with those in arteries have been recorded. The possible effect of the pulse upon the flow of lymph has been discussed.

Coronary Thromboendarterectomy for Angina Pectoris

Total occlusion of one or more major coronary arteries by atherosclerosis is characteristically found in the majority of patients with the clinical manifestations of severe angina pectoris.Sites of arterial obstruction in patients with severe angina pectoris may be localized precisely by coronary arteriography, and in selected cases it is possible to perform thromboendarterectomy under direct vision. The findings in a group of patients treated in this manner are presented and discussed. Results after a limited period of observation appear sufficiently encouraging to recommend this approach in the management of selected patients with intractable angina pectoris.

Effect of Total Pneumonectomy on Position of the Esophagus.

Summary Total pneumonectomy in dogs, without an associated paralysis of the diaphragm, was found to be followed by a marked deviation of the esophagus to the side from which the lung had been removed.

Effects of Primary Shock on Cardiac Output and Blood Pressure.

In a previous study, 1 the effects of uncomplicated hemorrhage on cardiac output and blood pressure were determined. Repeated removal of blood was usually associated with a decline in the cardiac output from 30 to 50% below the normal level before a marked diminution in the blood pressure occurs. Johnson and Blalock 2 found that secondary shock as a result of trauma to muscles, trauma to the intestines or burns is associated with a definite decrease in the output of the heart before the blood pressure is altered appreciably. On the contrary, the introduction of histamine 2 causes an initial decline in the blood pressure followed by a decrease in the cardiac output. Following the removal of the adrenal glands, 3 the blood pressure usually declines before the cardiac output is altered. Trauma to the central nervous system 4 is usually associated with a simultaneous decline in both the cardiac output and blood pressure. The alterations in the cardiac output and blood pressure in primary shock were determined in the present experiments in order to compare these changes with those observed in secondary shock. Dogs were profoundly anesthetized by sodium barbital administered intravenously. The dosage was 0.3 gm. per kilo of body weight. The control determinations of the cardiac output and blood pressure were performed approximately 2 hours after injection of barbital. The anterior abdominal wall of the animal was then struck many blows in rapid succession with flat surface of a board. This procedure occupied approximately 2 minutes. Thirty to sixty seconds later, the cardiac output and blood pressure were again determined. If free hemorrhage into the peritoneal cavity resulted from the traumatization, the experiment was discarded. A cannula that was placed in the femoral artery was used for the determination of the blood pressure. The cardiac output was computed by the Fick principle: Oxygen consumption per minute No. cc. of blood

Experimental Hypertension. Effects of Kieselguhr Injection and of Splanchnic Stimulation.

Several observers have determined the effects on the blood pressure of injecting multiple emboli into the renal arteries. Senator 1 injected liquid paraffin into the renal arteries of cats and no elevation of blood pressure occurred. Cash 2 injected insoluble Berlin blue into the renal arteries of dogs. The blood pressure did not become elevated. Similarly, no rise in the blood pressure of dogs was detected by Apfelbach and Jensen 3 following the injection of particles of charcoal. On the other hand, Maegraith and McLean 4 reported recently the results of experiments in which arterial hypertension was produced in rabbits by the injection of a suspension of Kiesel-guhr white into one renal artery. Even more interesting is their finding that the blood pressure returned to normal following the excision of the renal nerves. Renal denervation, or in fact total sympathectomy, 5 does not abolish in dogs the hypertension that is associated with partial constriction of the renal arteries by Goldblatt clamps. Because of this difference, the effect on the blood pressure of dogs of injecting Kieselguhr into the renal arteries has been determined. A total of 14 dogs were used. Eight died after intervals of one to 21 days following the introduction into the right renal artery of from 0.5 to 20 cc of 1% suspension of Kieselguhr white. None of these animals developed a rise in blood pressure as determined by needle puncture of the femoral artery. Varying degrees of destruction of the kidney substance were observed. Complete liquefaction followed the introduction of the large doses. The right kidneys of 6 dogs surviving for 20 to 35 days the injection of the right renal arteries with from 1.0 to 6.5 cc of Kieselguhr suspension were explored and changes varying from complete necrosis to a small hard kidney were found.

Renal Oxygen Utilization of Dogs with Experimental Hypertension.

Summary The variability of renal arterio-venous oxygen difference in fasting dogs with partial constriction of the renal artery with and without hypertension is similar to that of normal dogs.

THE EFFECTS OF CHANGES IN HYDROGEN ION CONCENTRATION ON THE BLOOD FLOW OF MORPHINIZED DOGS

The authors have recently studied the effects of partial respiratory obstruction on the respiration and circulation of the morphinized dog. In a previous communication (Blalock, Harrison and Wilson, 1925), it has been shown that when experimental respiratory obstruction is produced in dogs these animals develop a marked acidosis dependent on carbon dioxide retention and at the same time show an increase of from 40 to 200 per cent in the circulatory minute volume. The object of the present study was to determine whether an acidosis independent of respiratory obstruction was accompanied by an increased blood flow, and, if this occurred, to observe the effect of the administration of alkali on the circulation in normal dogs and in dogs to which acid had been administered.

William Stewart Halsted, an appreciation on the centenary of his birth.

William Stewart Halsted, who was destined to work and to produce in a golden era in medicine, was born in New York City in 1852. He was graduated from Yale University in arts in 1874 and from the College of Physicians and Surgeons in medicine in 1877. It was while serving an internship at Bellevue that he first met William H. Welch, who had just returned from Germany where he had been working in the basic sciences in the laboratories of Julius Cohnheim and others. At that time medical education in this country was in a deplorable state. There were many medical schools, none of university caliber, and all proprietary, whereas there were about 20 university medical schools in Germany. About this time Johns Hopkins, a Baltimore merchant and banker, left his fortune for the establishment of a university and a hospital, the latter to be a part of the