THE ROLE OF THE ADRENAL CORTEX IN ACUTE ANOXIA

Physiological indices and liver gene expression related to glucose supply in Brandt's vole (Lasiopodomys brandtii) exhibit species- and oxygen concentration-specific responses to hypoxia

Brandt's vole (Lasiopodomys brandtii) is a species with hypoxia tolerance, and glucose serves as the primary energy substrate under hypoxia. However, the glucose supply in Brandt's voles under hypoxia has not been studied. This study aimed to investigate characteristics in physiological indices and liver gene expression associated with glucose supply in Brandt's voles under hypoxia. Serum glucose of Brandt's voles remained stable under 10% O2, increased under 7.5% O2, and decreased under 5% O2. Serum lactate increased under 10% O2, decreased under 7.5% O2, increased at 6 h and decreased at 12 h under 5% O2. Liver glycogen increased under 10% O2, remained constant under 7.5% O2, and reduced under 5% O2. Pepck and G6pase expression associated with gluconeogenesis decreased under 10% O2, while Pepck expression decreased and G6pase expression increased under 7.5% and 5% O2. Regarding genes related to glycogen metabolism, Gys expression decreased at all oxygen concentrations, Phk expression increased under 5% O2, and Gp expression increased under 7.5% and 5% O2. The alterations in glucose, lactate, liver glycogen, and gene expression related to glycogenolysis in Kunming mice (Mus musculus, control species) are similar to discovery of Brandt's voles under 7.5% O2, but gene expression involved in gluconeogenesis and glycogen synthesis increased. The findings suggest that Brandt's voles are more tolerant to hypoxia than Kunming mice, and their physiological indices and liver gene expression related to glucose supply exhibit species- and oxygen concentration-specific responses to hypoxia. This research offers novel insights for studying hypoxia tolerance of Brandt's voles.

Changes in expression of genes related to glucose metabolism in liver and skeletal muscle of rats exposed to acute hypoxia

The aim of this study was to determine changes in gene expression associated with glucose metabolism in the liver and soleus muscles of rats exposed to hypoxia to improve work capacity under high altitude conditions. Rats were divided into normobaric normoxia (control) and normobaric hypoxia (hypoxia) groups (n = 7 each), and the hypoxia group was exposed to 10.5% oxygen for 90 min. Glucose metabolism-related gene expression was examined by real-time polymerase chain reaction. In the liver, the expression levels of the glucose utilization-related genes solute carrier family 2 member 1, glucokinase, and liver-type phosphofructokinase and the gluconeogenesis-related gene phosphoenolpyruvate carboxykinase 1 (Pck1) were significantly increased upon hypoxic exposure. In contrast, gene expression in the soleus was unchanged, with the exception of Pck1. The results suggest that under hypoxia, both glucose utilization and gluconeogenesis are accelerated in the liver, and liver glycogen is degraded to maintain blood glucose level.

The Effects of Convulsive Therapy on the Excretion of Cortins and Ketosteroids

Electroshock therapy, first introduced to this country by Fleming, Golla and Grey Walter in 1939, has long passed its period of probation and is now universally accepted as active and effective. Yet its mode of action is still unknown. The variety of theories propounded to explain its action establishes only the degree of our uncertainty. To advance our knowledge of its mode of action has been the aim of the work described in this paper.

The adrenal gland and the cardiovascular changes in acute anoxic anoxia in dogs

The hyperkinetic circulatory state observed in intact anesthetized dogs at the end of a 15 minute period of breathing 6 per cent oxygen in nitrogen was absent in a similar series of dogs acutely adrenalectomized by the ligation technie. Blood removed from intact animals at the end of the anoxic period and infused into normal assay dogs produced a rise in cardiac output in the latter which was not observed with comparable infusions of normal blood or blood removed from adrenalectomized anoxic dogs. The transferable agent demonstrated by this study is considered responsible for the rise in cardiac output in the anoxic donor. It is suggested that this agent arises from the adrenal medulla.

Synergistic effects of acute hypoxemia and hypercapnic acidosis in conscious dogs. Renal dysfunction and activation of the renin-angiotensin system

The effects of acute hypoxemia and hypercapnic acidosis were examined in five unanesthetized dogs in which sodium intake was controlled at 80 mEq/24 hours for 4 days prior to study. Each animal was studied during combined acute hypoxemia and hypercapnic acidosis (Pao2 = 36 +/- 1 mm Hg, Paco2 = 52 +/- 1 mm Hg, pH = 7.18 +/- 0.02), acute hypoxemia alone (Pao2 = 32 +/- 1 mm Hg, Paco2 = 32 +/- 1mm Hg, pH = 7.34 +/- 0.01), and acute hypercapnic acidosis alone (Pao2 = 82 +/- 2 mm Hg, Paco2 = 51 +/- 1 mm Hg, pH = 7.18 +/- 0.02). Although mean arterial pressure, cardiac output, and heart rate increased during combined hypoxemia and hypercapnic acidosis, effective renal plasma flow and glomerular filtration rate decreased. In addition, filtered sodium load and urinary sodium excretion decreased during combined hypoxemia and hypercapnic acidosis. Either acute hypoxemia or hypercapnic acidosis alone resulted in increased mean arterial pressure, cardiac output, and heart rate. However, in contrast to their combined effects, renal hemodynamic function was unchanged and natriuresis was observed. Measurement of plasma renin activity and angiotensin II concentrations indicated that hypoxemia or hypercapnic acidosis alone resulted in moderate activation of the renin-angiotensin system. Moreover, combined hypoxemia and hypercapnic acidosis acted synergistically resulting in major renin-angiotensin activation. Systemic angiotensin II blockade using 1-sarcosine, 8-alanine, angiotensin II (2 micrograms/kg per min) during combined acute hypoxemia and hypercapnic acidosis resulted in decreased renal hemodynamic function. We conclude that acute hypoxemia and hypercapnic acidosis act synergistically to increase mean arterial pressure, diminish renal hemodynamic function and activate the renin-angiotensin system. Systemic angiotensin inhibition studies suggest activation of the renin-angiotensin system maintains renal hemodynamic function during combined hypoxemia and hypercapnic acidosis, instead of mediating the renal vasoconstriction.