Ben H. Douglas

Instantaneous Increase in Mean Circulatory Pressure and Cardiac Output at Onset of Muscular Activity

In dogs with their spinal cords cut, sudden maximal muscular contraction in the lower half of the body caused the mean circulatory pressure to rise instantaneously to three times normal and the cardiac output to rise to an average of 40 per cent above normal. This instantaneous effect was not blocked by sympathetic blockade with hexamethonium but was blocked by skeletal muscle blockade with decamethonium. Furthermore, because of the transected cord, no cardiac reflex effects were observed. Therefore, it was concluded that skeletal muscle activity compresses the intra-muscular and intra-abdominal vessels and thereby increases the mean circulatory pressure. Evidence is presented to show that this, in turn, translocates blood into the heart and that the heart then responds in conformity with Starlings principle of cardiac adaptation to increase the cardiac output.

The effects of propranolol on cholesterol-induced atheromatous lesions☆

Abstract The effects of propranolol on cholesterol-induced atheromatous lesions in rabbits and on the calcium content of the vascular tissue of these animals were studied. The calcium content of normal rabbit aortae was significantly lower than that of the aortae of rabbits receiving a 2% cholesterol supplemented diet. The calcium content from rabbit aortae which had received a 2% by weight cholesterol diet was significantly higher than that of the aortae of rabbits which received propranolol plus cholesterol, and of the aortae of rabbits which received a normal diet plus propranolol. Histological results showed atheromatous plaques within the intimal layer of the aortae of the cholesterol group. Some of the rabbits which received propranolol plus cholesterol had lesions, but these were less severe than those of the cholesterol group. These results indicate that propranolol affects fat and calcium metabolism in the aorta.

Effect of Changes in Salt Intake on Arterial Pressure and Renal Function in Partially Nephrectomized Dogs

Approximately 70% of the total renal tissue was removed in 11 dogs. Control values were then established for mean arterial pressure, urine and plasma sodium concentrations, blood urea nitrogen, glomerular filtration rate, total body weight, and rate of urine formation for these dogs and for two dogs whose kidneys were left intact. Two of the partially nephrectomized dogs were allowed to drink water for the duration of the study while the other animals were required to drink 0.9% sodium chloride solution for various periods of time. The increased salt intake resulted in a 30% to 40% increase in arterial pressure within 48 to 72 hours; plasma sodium concentration increased concomitantly with the development of hypertension. The elevated pressure could be reduced to normal levels within 24 hours by simply allowing the dogs to drink tap water again. Similar results were obtained in a single dog in which renal function had fortuitously been reduced by chronic pyelonephritis.

Circulatory changes following prolactin administration

Abstract This study was designed to determine the effect of prolactin on blood pressure, blood volume, and response to angiotensin. Ten rats served as controls, 10 received 250 μg of prolactin per day, and 10 received 2.5 mg. of prolactin per day. Prolactin produced a decrease in blood pressure and an increase in blood volume. The animals which received the larger dose (2.5 mg. per day) of prolactin were hyporesponsive to angiotensin. The animals which received the smaller dose of prolactin had a response to angiotensin similar to that of the control animals. Prolactin secretion may produce or modify some of the circulatory changes observed in late pregnancy.

Response of Mineralocorticoid Hypertensive Animals to an Angiotensin I Converting Enzyme Inhibitor

Summary The effect of the angiotensin I converting enzyme inhibitor, SQ-14,225 on DCA-NaCl hypertension was determined. The inhibitor did not affect the development of DCA-NaCl hypertension. It also did not affect the blood pressure of animals with established DCA-NaCl hypertension. This suggests that the SQ-14,225 exerts its antihypertensive effect purely by decreasing angiotensin II and not by increasing vasodilator kinins.

Enkephalin contents reflect noradrenergic large dense cored vesicle populations in vasa deferentia

Opioid peptides including met- and leu-enkephalins are co-stored with catecholamines at similar concentrations in highly purified chromaffin granule fractions from bovine adrenal medulla and large dense cored vesicle (LDV) fractions from bovine splenic nerve. An initial attempt was made to test the universality of the co-storage of enkephalins in LDVs of sympathetic nerves. Based on a number of practical considerations, vasa deferentia were chosen from seven species. Leu-and met-enkephalin contents were quantitated by radio-immunoassays and norepinephrine by HPLC with electrochemical detection. Norepinephrine contents varied 11-fold and generally paralleled the density of sympathetic innervation among the species as reported in the literature. Leu-enkephalin contents varied 26-fold, generally paralleling the percentage composition of LDVs in the respective terminal varicosities among the species and animal size (axonal length). Met-enkephalin contents varied 20-fold, generally paralleling the density of sympathetic innervation, but not the percentage LDVs. Various amounts of met-enkephalin were also likely stored in cells other than sympathetic nerves, including chromaffin-like cells, the incidence of which varied according to species. Thus, the met- to leu-enkephalin ratios varied from 1.2:1 in dog; 1.7-1.9:1 in rabbit, cat and bull; 2.9:1 in man; 8.2:1 in rat; and essentially only met-enkephalin in guinea pig. The data imply differences in the processing of preproenkephalins in the same tissue of different species as well as in different cells of that tissue.

Effect of hypervolemia and elevated arterial pressure on circulatory dynamics of pregnant animals

Abstract In an attempt to gain insight into some of the mechanisms which may underlie the changes in the circulatory system that accompany pregnancy, the effect of hypervolemia and elevated arterial pressure on the mean circulatory pressure was studied. There was a linear relationship between mean circulatory pressure and blood volume and the mean circulatory pressure increased when the arterial pressure was elevated. These data indicate that hypervolemia is responsible for some of the hemodynamic alterations which accompany pregnancy.

Placental transfer of imipramine, a basic, lipid-soluble drug

Abstract The present study was designed to determine the rate of placental transfer of imipramine (Tofranil), an antidepressive agent which is widely distributed in tissues. It was also designed to determine the time required for the establishment of equilibrium between the maternal and fetal systems. Twenty rats which were in the third trimester of pregnancy received an intramuscular injection of 10 mg. per kilogram of imipramine. The animals were killed at 1, 3, 5, 10, and 20 minute intervals by exsanguination, and the concentration of the drug in the maternal plasma and fetal tissue determined. Equilibrium between the two systems was established within 3 minutes. It was suggested that this rapid equilibrium between the maternal and fetal systems was due to the high lipid solubility of imipramine.

Postterm blood pressure elevation produced by uterine wrapping

Abstract Chronic uterine ischemia produced a postterm elevation of blood, pressure in rats and a postterm elevation of proteinuria in rabbits. These unexpected findings may be of the same origin as that of toxemia of pregnancy, but as the cause is unknown we cannot equate them. Chronic uterine ischemia per se will not produce preeclampsia in the experimental animal. There were no changes in arterial pressure or proteinuria during the course of pregnancy and there was a conspicuous absence of edema.

Effects of reserpine on blood pressure and vascular electrolytes in hypertension.

Abstract Reserpine lowered the blood pressure of desoxycorticosterone (DCA)-hypertensive rats. It also caused a decrease in aortic sodium and potassium contents. The electrolyte changes parallelled the changes in blood pressure and suggested that there is a relation between them.