Significant Increase In Blood Flow Research Articles

Effects of indomethacin on renal hemodynamic alterations caused by arterial and ureteral pressure changes in rabbits.

Roles of prostaglandins in renal autoregulation and the distribution of cortical blood flow were studied in anesthetized rabbits, by means of prostaglandin synthesis inhibition. Within the range from 80 to 130mmHg in renal perfusion pressure, a constancy of renal blood flow was maintained. With an abrupt elevation of perfusion pressure from 100 to 130mmHg, blood flow did not alter in any regions of the cortex. In contrast, when perfusion pressure was reduced from 100 to 80mmHg, blood flow decreased in the outer cortex with reciprocal increase in the inner cortex. These hemodynamic changes were not affected by indomethacin. Acute ureteral pressure elevation to 50mmHg resulted in a redistribution of cortical flow to the inner cortex without significant change in renal blood flow. This redistribution was inhibited by indomethacin. During ureteral pressure elevation, autoregulation was impaired. In this situation, a rise of perfusion pressure produced a significant increase in blood flow in the outer cortex without significant change elsewhere. A reduction of perfusion pressure gave rise to significant decrease in flow in the outer cortex without an increase in the inner cortex. In indomethacin-treated rabbits, ureteral pressure elevation impaired autoregulation slightly but not significantly. These findings suggest 1) good autoregulatory capability in all regions of the renal cortex; and 2) a minor role of prostaglandins in the development of renal autoregulation in normal rabbits but a partial contribution to the impairment of autoregulation during ureteral pressure elevation.

Haemodynamic studies in renal artery stenosis.

With the aid of an electromagnetic flowmeter and a mechano-electrical pressure transducer, peroperative renal artery blood flows and pressures in the aorta and the renal artery distal to the stenosis were measured in 48 patients with renovascular hypertension before and after renal artery reconstruction. Calculations of pressure difference across the stenosis and resistances over the stenosis and the renal parenchyma were made. There was a significant blood flow increase through the renal artery after arterial reconstruction in all patients, irrespective as to whether they were normotensive, improved or failures postoperatively. The pressure difference across the stenosis after reconstruction was eliminated in all 3 groups of patients. The highest resistances over both the stenosis and the renal parenchyma before arterial reconstruction were found in the normotensive group, but there was no significant variation between the 3 groups. After reconstruction, a significant decrease in resistance over the renal parenchyma was found in the normotensive and the improved group of patients. The resistance of the stenosis was higher than over the renal parenchyma only in the postoperatively normotensive patients. This indicates that the removal of a resistance over the renal artery stenosis, that is higher than that over the renal parenchyma, gives the most favourable long-term results concerning normalization of the blood pressure.

The local hemodynamic effects of operation in a bloodless field.

Skeletal muscle blood flow and transport function were investigated in 25 patients operated on for a knee injury in a bloodless field. With a double-isotope-clearance technique, measurements were carried out in the operated leg immediately after re-establishment of blood flow, and 1-2 days postoperatively in both the operated and the non-operated leg. A significant increase in blood flow and transport function was registered immediately after release of the tourniquet. The initial maximal hyperemic flow and transport responses were inversely related to the duration of the occlusion. The peak of the blood flow response was more marked and somewhat earlier in the patients with a short duration of occlusion (less than or equal to 60 min) than in those with longer occlusions. 9 of 16 operated legs showed a maximal transport function 1-2 days postoperatively. Peripheral vascular resistance decreased after re-establishment of blood flow. The blood flow in the non-operated leg showed no changes after release of the tourniquet in the operated leg.

Effect of a Vasopressin Analogue (Na‐glycyl‐gIycyl‐glycyI‐[8‐lysine]‐vasopressin) on Organ Blood Flow in the Pregnant Guinea Pig

Abstract Na‐triglycyl‐(8‐lysine)‐vasopressin (TGLVP) was administered intravenously to pregnant guinea pigs and the effect on regional blood flow examined by the radioactive microsphere technique. A dose of 10 μg/kg TGLVP caused an elevation of the mean arterial blood pressure, from 6.4 to 11.1 kPa, a significant reduction in blood flow to the gut, skin and skeletal muscle and a significant increase in blood flow to the spleen. The number of 15 ± 5 urn microspheres reaching the lungs diminished significantly after 10 μg/kg TGLVP, indicating that this dose constricted arterio‐venous short circuits in the systemic circulation. There was also a decrease in blood flow to the urogenital tract, including the placentae. When 3 μg/kg TGLVP was injected, the mean arterial blood pressure rose from 6.5 to 8.7 kPa and there was no longer any consistent effect on maternal placental blood flow. It is suggested that pregnancy constitutes a contraindication for TGLVP, since a reduction in uterine and maternal placental blood flow might occur with clinically relevant doses.

Effect of a Vasopressin Analogue (Nα‐glycyl‐glycyl‐glycyl‐[8‐lysine]‐ vasopressin) on Organ Blood Flow in the Pregnant Guinea Pig

Nalpha-triglycyl-(8-lysine)-vasopressin (TGLVP) was administered intravenously to pregnant guinea pigs and the effect on regional blood flow examined by the radioactive microsphere technique. A dose of 10 mug/kg TGLVP caused an elevation of the mean arterial blood pressure, from 6.4 to 11.1 kPa, a significant reduction in blood flow to the gut, skin and skeletal muscle and a significant increase in blood flow to the spleen. The number of 15 +/- 5 mum microspheres reaching the lungs diminished significantly after 10 mug/kg TGLVP, indicating that this dose constricted arterio-venous short circuits in the systemic circulation. There was also a decrease in blood flow to the urogenital tract, including the placentae. When 3 mug/kg TGLVP was injected, the mean arterial blood pressure rose from 6.5 to 8.7 kPa and there was no longer any consistent effect on maternal placental blood flow. It is suggested that pregnancy constitutes a contraindication for TGLVP, since a reduction in uterine and maternal placental blood flow might occur with clinically relevant doses.

Circulatory response to systemic infusion of norepinephrine in the pregnant ewe

Seven pregnant ewes from 100 to 137 days of gestation were infused with systemic doses of norepinephrine and uterine arterial flow dose-response curves were determined. A constant infusion of norepinephrine at a mean rate of 0.24 μg per minute per kilogram led to a 39.3 per cent decrease in total uterine arterial blood flow as measured with isotope-labeled microspheres while systemic pressure was unaltered. At this dose the reduction in endometrial blood flow (−64 per cent) was significantly greater than that in either the myometrium (−45 per cent) or placental cotyledons (−31 per cent) (p < 0.005). Significant decreases in blood flow to small bowel, skeletal muscle, vagina, cervix, Fallopian tubes, kidneys, spleen, pancreas, and mammary gland were documented. There were no significant increases in blood flow. This study demonstrates that during the period of pregnancy studied, the overwhelming response to norepinephrine is vasoconstriction and that the vascular beds of all the tissues of pregnant uterus are sensitive to the alpha-adrenergic effects of norepinephrine.

Early biochemical and hemodynamic changes after operation in a bloodless field.

Biochemical and hemodynamic changes during and after operation in a bloodless field have been investigated in 13 patients. The patients were athletes between the age of 21 and 38 years who were healthy except for an inveterate ligament injury of the knee joint. Capillary blood flow in the tibialis anterior muscle was measured by the radioactive-Xenon-clearance technique. Fine plastic catheters for blood sampling were inserted into both femoral veins and into one radial artery. A significant increase in blood flow occurred immediately after release of the occlusion. After release of the tourniquet, there was a marked decrease in pH both in the venous blood draining the operated leg and in the arterial blood. 40 min after release of the tourniquet, there was still a significant decrease in base excess. An increase of venous pO2 in the blood draining the operated leg was observed after re-establishment of blood flow. The estimated oxygen consumption was increased in the operated leg the first 10 min after tourniquet release.

Effects of a carbonic anhydrase inhibitor on cerebral blood flow in geriatric patients.

A carbonic anhydrase inhibitor (UK-12,130) was shown to increase cerebral blood flow in mildly demented geriatric patients. Oral administration caused a significant increase in blood flow at two different dose levels; this persisted for at least six weeks, which was the duration of the longest study. There was no consistent improvement in mentation during treatment. Blood blow was measured by the washout of 133Xe after inhalation of this inert gas.

Dopamine effects on the intestinal circulation

The effects of intra-arterial infusion of dopamine on superior mesenteric artery blood flow, intestinal flow, intestinal oxygen consumption, and capillary density were studied in anesthetized dogs before and after blockade of dopamine receptors with haloperidol and after beta-adrenergic receptor blockade with propranolol. Mesenteric blood flow to a distal segment of the small intestine was measured with an electromagnetic blood flow-meter and intestinal oxygen consumption was calculated from the measured arteriovenous oxygen difference across the intestine and total blood flow. Intestinal capillary density was estimated from the clearance of 86Rb. In normal animals prior to dopaminergic or beta-adrenergic blockade, dopamine caused a dose-related decrease in mesenteric blood flow, intestinal oxygen consumption, and 86Rb clearance. Only the lowest dose of the drug, 1 mug/Kg.-min., did not significantly change the intestinal capillary density. In dogs pretreated with the dopamine receptor, antogonist, haloperidol, dopamine (20 mug/Kg.-min.) caused a significant increase in blood flow and oxygen consumption and did not significantly alter the number of perfused intestinal capillaries. These increases in haloperidol-blocked animals administered dopamine were reversed by propranolol. Our results indicate that dopamine caused smooth muscle contraction in mesenteric arterioles and precapillary sphincters, thereby producing intestinal ischemia and hypoxia. These findings with haloperidol and propranolol indicate that dopamine stimulates at least two different receptors in the canine mesenteric vascular bed: a constrictor receptor blocked by haloperidol and a dilator receptor blocked by propranolol.

Gas exchange in the pulmonary collateral circulation of dogs. Effects of alveolar hypoxia and systemic hypoxemia.

The left main pulmonary artery was ligated in 7 fully grown dogs. This resulted in an enlarged pulmonary collateral (systemic) flow to the left lung. By collecting gas from each lung separately, gas exchange in the pulmonary collateral circulation was studied and compared to that in the normal contralateral side. Studies were done repeatedly during a period of 3 years. Compared to that in the preoperative period, the ligated (left) side showed a decrease in ventilation (42.5 to 34.5 per cent of total), a marked increase in wasted ventilation (0.30 to 0.55), and a marked decrease in O2 uptake (45 to 11.2 per cent of total) and CO2 production (27.5 to 15.3 per cent of the total). There were no changes in arterial blood gases or pH. A significant, sustained, systemic hypertension was noted in all dogs in which the left main pulmonary artery was ligated (190/120). The mean blood flow through the pulmonary collateral circulation of the left lung with the dogs breathing room air was estimated to be 94 ml per min. When the dogs were made hypoxemic by breathing 12 per cent O2 through the normal right lung, there was a marked increase in pulmonary collateral (systemic) flow to the contralateral side (194 ml per min). This resulted in an increase in O2 consumption (29.4 per cent of total) and CO2 production (23.1 per cent of total) of the left lung. When the dogs were given 12 per cent O2 to breathe through the ligated left lung, there was no change in arterial PO2. There was a significant increase in blood flow through the pulmonary collateral circulation to 136 ml per min. Because of the gradient of O2 between the blood flowing into the left lung and that present in the alveoli, there was a net production of O2 from the left lung of 4.5 ml per min. When the pulmonary systemic circulation participates in gas exchange, it appears to increase during hypoxemia as well as during alveolar hypoxia.

Effect of dihydroergotamine on perpheral circulation during epidural anaesthesia in man.

The effect of intravenous administration of dihydroergotamine (DHE) on regional blood flow in the forearm and calf after pharmacological nerve blockade of the lower body induced by epidural anaesthesia has been studied in 13 subjects. After anaesthesia, DHE induced a significant increase in blood flow in the forearm with intact innervation and a significant decrease in blood flow in the nerve-blocked calf. On the average, the arterial blood pressure increased slightly. The calculated local vascular resistance increased in the nerve-blocked calf, probably due to a direct myogenic constrictive effect of DHE. In the intact forearm, local vascular resistance decreased. The results indicate that DHE exerts a complex effect on resistance vessels in addition to its well-known effect on the capacitance vessels.

Cardiovascular effects of venous blood from missile wounds.

A cross-infusion model including two dogs was used. At intervals 20 ml of blood from the iliac vein of one dog (donor), was injected during 60 sec into the iliac artery in which flow was measured electromagnetically in another dog (recipient). 1 min after missile trauma of the hind leg of the donor, the withdrawn venous blood possessed strong dilator property, manifesting itself by a transient, significant increase of blood flow in the registered artery of the recipient. This dilator property of venous blood from the traumatized region was, however, only apparent following wounding by missiles of high velocity.

Effects of vagal stimulation on glucagon and insulin secretion.

Electrical stimulation of the distal cut end of the vagus nerves was performed at the diaphragmatic level in anesthetized dogs to study its effects on glucagon and insulin output from the pancreas. Stimulation of the dorsal vagus nerve increased both blood flow and plasma glucagon and insulin concentrations in the cranial pancre-aticoduodenal vein, resulting in a greater aug-mentation of bihormonal output. A significant enhancement was observed in femoral arterial plasma insulin, but not in circulating plasma glucagon. Plasma glucose concentration rose gradually during stimulation. Atropinization abolished the augmentation of glucagon and insulin output seen in response to stimulation of the dorsal vagus. Stimulation of the ventral vagus nerve resulted in no statistically significant increase in blood flow, plasma hormone concentration and plasma glucose level. These results indicate that physiological activation of the vagus nerve may regulate both insulin and glucagon secretion from the pancreas islet v...

Blood flow in otorhinologic tissue after histamine and papaverine.

A method has evolved that allows one to quantitatively measure nutritional blood flow in the labyrinth. Several otic symptoms (e.g., sudden hearing loss) are thought to be due to decreased labyrinthine blood flow. Our aim was to test two common vasodilators, histamine and papaverine, to determine if they were effective in increasing blood flow to otic tissue. The method employs the intracardiac injection of radioactive microspheres (15 μ in diameter). These spheres become embolized in the microcirculation and provide a measure of blood flow in ml/gm/min. Histamine or papaverine were infused intravenously for five min at several doses. Blood flow was measured before and after infusion. Both drugs cause a significant increase in blood flow to temporal bone tissue if used in the appropriate dose range, i.e., about 1 ug/kg/min for histamine and 0.5 mg/kg/min for papaverine. If the dose of either drug is increased to the point that causes a drop of more than 15 mm Hg in systemic blood pressure, there is either no increase or a drop in otic blood flow. This reversal of the drug response is felt to be due to autoregulatory mechanisms in intracranial blood vessels.

The effect of glucagon on the distribution of blood flow in the splanchnic area

The blood flow in different splanchnic organs was investigated in rats following glucagon administration utilising the 86Rb-distribution method of Sapirstein (5). There was a significant increase in blood flow to the kidneys (32 %) and to the duodenum (44 %) following 100 μg/kg glucagon. In addition, blood flow was enhanced to the liver (67 %) and to the pancreas (72 %) following 500 μg/kg glucagon. An infusion of 0.5 μg/kg/min produced only a slight increase in renal blood flow (18 %) and the arterial systematic pressure remained more or less constant after glucagon administration. The doses required for comparable effects are much higher in rats than in dogs (Kock et al. [1]). Moreover, the sensitivity of the various splanchnic organs to glucagon differs; thus, blood flow in the gastric mucosa tended to decrease, as already described by previous workers.

Basilar arterial flow changes elicited by hydralazine hydrochloride, isoxsuprine hydrochloride and nylidrin hydrochloride.

The influence of infusion of hydralazine, isoxsuprine or nylidrin on blood flow in the basilar artery and on systemic blood pressure was investigated in anesthetized dogs. The drugs were administered individually in 1-mg and 2-mg doses and in various combinations of 1 mg each by injection just proximal to the formation of the basilar artery. Analysis of the data revealed significant increases in blood flow (P&lt;0.05) immediately after injection and a statistically significant (P&lt;0.05) interaction between time and drug. No statistical differences were found in comparisons of the effects of the 1-mg and 2-mg dose levels for any of the drugs. At either dosage isoxsuprine and nylidrin caused a 16% to 28% decrease in systemic blood pressure, while hydralazine effected a more moderate, approximately 5%, decrease. Basilar flow responded to 1-mg combinations of isoxsuprine/hydralazine and nylidrin/hydralazine with a consistent 25% to 30% increase. However, the flow response to nylidrin/isoxsuprine was unpredictable. The data indicate that these substances increased basilar arterial flow by inducing a transient local vasodilatation. The effects of the drug combinations on flow were in general synergistic and positive, and were similar to those after infusion of the individual drugs, except for a somewhat slower initial response and a longer duration.

Morphine-induced redistribution of cardiac output in the unanesthetized monkey.

Regional blood flow measurements were made using the radioactive microsphere technique of Rudolph and Heymann [13] before Histamine and 3 times after the i.v. infusion of 2 mg/kg morphine in 9 unanesthetized monkeys restrained in horizontally tilted primate chairs. The dose was chosen after response curves established its minimal but consistent hypotensive effects. Although little systemic hemodynamic change was observed, the morphine evoked significant increases in blood flow to the heart, brain and bone, which lasted up to 1¹/₂ h. The changes in regional blood flow outlasted the effects on blood pressure. Initially blood flow to the bronchial arteries was reduced to 50% of baseline. These changes were associated with depressed respiration, decreased pH and PO₂ and an increased PCO₂ of arterial blood. Arterial blood levels of histamine were not significantly changed after the morphine infusion; therefore, histamine cannot be considered the mediator of the changes in regional blood flow.

Effects of adenosine compounds on renal function and renin secretion in dogs.

In anesthetized salt-depleted dogs, infusion of adenosine (20 to 500 µg/min) directly into a renal artery induced an initial decrease of renal blood flow for 1 to 2 minutes but did not change or slightly increased this flow during the steady state. Statistically significant decreases occurred in glomerular filtration rate, filtration fraction, sodium excretion, and renal venous renin activity. Calculated afferent arteriolar resistance increased and efferent resistance decreased. 5'-AMP (50 to 200 µg/min) induced changes which were smaller but qualitatively similar to those of adenosine. ATP (50 to 500 µg/min) induced no initial reduction in blood flow, and, during the steady state, caused a significant increase in blood flow and decreases in glomerular filtration rate, filtration fraction, sodium excretion, and renal venous renin. Efferent resistance decreased but afferent resistance did not change. Cyclic AMP (1 to 5 mg/min) caused a very small initial transient reduction in blood flow but induced changes similar to those of ATP during the steady state. Inosine (200 µg/min) and inosine-5'-monophosphate (50 to 200 µg/min) produced no detectable effects. It is suggested that adenosine or 5'-AMP may be normal mediators of both autoregulation and renin secretion.

Dynamics of blood flow in thromboangiitis obliterans

The resting blood flow in the horizontal position in the foot-leg of seven subjects with moderately advanced thromboangiitis obliterans was found to be within normal limits, as measured by the plethysmographic method. The release of arterial occlusion in the thigh resulted in no significant increase in blood flow. No initial increase in limb volume and no significant cardiac acceleration followed the release of arterial occlusion in these subjects. Heat or lumbar sympathetic ganglionectomy, alone or in conjunction with arterial occlusion, was no more effective in increasing the volume of blood flow than was simple arterial occlusion. After the release of arterial occlusion, an initial decrease in blood flow was manifest. This was not prevented by local heat or by sympathetic ganglionectomy.

Sudden occlusion of the arteries of the extremities: McKechnie, R. E., and Allen, E. V.: Surg., Gynec. & Obst. 63: 231, 1936

The resting blood flow in the horizontal position in the foot-leg of seven subjects with moderately advanced thromboangiitis obliterans was found to be within normal limits, as measured by the plethysmographic method.The release of arterial occlusion in the thigh resulted in no significant increase in blood flow. No initial increase in limb volume and no significant cardiac acceleration followed the release of arterial occlusion in these subjects.Heat or lumbar sympathetic ganglionectomy, alone or in conjunction with arterial occlusion, was no more effective in increasing the volume of blood flow than was simple arterial occlusion.After the release of arterial occlusion, an initial decrease in blood flow was manifest. This was not prevented by local heat or by sympathetic ganglionectomy.