Effects of insulin on plasma fibrinogen levels in rats submitted to tissue injury or ACTH administration

Summary Insulin is necessary to produce an increase of plasma fibrinogen in rats submitted to tissue injury or ACTH administration. This increase is more significant when endogenous or exogeneous excess of insulin is present, while in uninjured rats the absence or excess of insulin does not modify plasma fibrinogen.     

Effects of epinephrine on plasma fibrinogen levels in rats submitted to tissue injury

Summary Tissue injury (laparotomy) produces an increase in plasma fibrinogen. This increase is inhibited by the removal of the adrenal medulla, but injection of epinephrine in laparotomized-medullectomized rats returns fibrinogen levels to values similar to those observed in only laparotomized rats. Epinephrine administration to laparotomized rats increases the fibrinogen compared with the group of laparotomized rats without treatment, but epinephrine by itself does not modify plasma fibrinogen levels in uninjured rats. Epinephrine is apparently responsible for the increase of plasma fibrinogen in rats subjected to tissue injury, probably through beta adrenergic stimulation.     

Effects of adrenal demedullation combined with chemical sympathectomy on cold-induced responses of endocrine pancreas in rats

Adrenal demedullation combined with chemical sympathectomy with 6-hydroxydopamine (ACS) lowered plasma glucagon and insulin levels in rats. Acute cold exposure increased plasma glucagon in both ACS and control rats, while it increased plasma insulin only in ACS rats. ACS rats responded to cold with a smaller increase in plasma glycerol and a more pronounced elevation of plasma free fatty acids.     

Plasma fibrinogen response in the rat after thyroid stimulating hormone therapy

Thyroid Stimulating Hormone (TSH) increased the levels of plasma fibrinogen in the presence or absence of the thyroid gland. This finding suggests that this hormone produces an elevation of fibrinogen in rats by an extrathyroideal mechanism.     

Effect of hyperkalemia on insulin secretion

Summary The effect of hyperkalemia on insulin secretion remains undefined. We evaluated portal and peripheral insulin levels in anesthetized dogs after infusions of KCl. The mean maximal increase in peripheral plasma potassium at infusion rates of 0.2 mEq/kg/h was 0.68±0.20 mEq/l. There were no significant increases in either portal or peripheral insulin levels. In contrast, in six dogs whose plasma potassium concentration increased in each case by more than 2.0 mEq/l (infusion rate of 0.5 mEq/kg/h), portal insulin levels increased fivefold (p<0.05). We conclude that only marked increases in plasma potassium concentration stimulate pancreatic insulin secretion.     

Studies on plasma fibrinogen level in pre-eclampsia and eclampsia

Summary The plasma fibrinogen level of maternal blood has been estimated in 30 cases of pre-eclampsia, 60 cases of eclampsia and 35 cases of normal pregnancy of 3rd trimester. The plasma fibrinogen value increased by about 70% and 145% in pre-eclampsia and eclampsia, respectively. In essential hypertension, the fibrinogen level remains more or less the same as in normal pregnancy.     

Effect of hyperkalemia on insulin secretion

The effect of hyperkalemia on insulin secretion remains undefined. We evaluated portal and peripheral insulin levels in anesthetized dogs after infusions of KCl. The mean maximal increase in peripheral plasma potassium at infusion rates of 0.2 mEq/kg/h was 0.68 +/- 0.20 mEq/l. There were no significant increases in either portal or peripheral insulin levels. In contrast, in six dogs whose plasma potassium concentration increased in each case by more than 2.0 mEq/l (infusion rate of 0.5 mEq/kg/h), portal insulin levels increased fivefold (p less than 0.05). We concluded that only marked increases in plasma potassium concentration stimulate pancreatic insulin secretion.     

Effect of chronic alloxan diabetes and insulin treatment on adipose tissue lipid composition of rats

Summary Decreased content of the adipose tissue lipids was observed in chronic alloxan diabetic rats and was restored to normal with insulin treatment. Prolonged insulin treatment in normal rats also resulted in increase of the lipid content of the adipose tissue.     

L-arginine and pancreatic islet blood flow in anesthetized rats

The aim of the present study was to see if L-arginine, which induces insulin release and is a precursor of the endothelial-derived relaxing factor nitric oxide, affects whole pancreatic and/or islet blood flow. For this purpose, anesthetized male Sprague-Dawley rats were injected intravenously with either saline or L-arginine (25, 100 or 250 mg/kg body weight). All doses of arginine caused a slight increase in blood glucose concentration, while the highest dose (250 mg/kg body weight) also increased insulin concentration. However, no changes in either mean arterial blood pressure, whole pancreatic or islet blood flow could be discerned with any of the doses of arginine used. It is concluded that insulin release is not necessarily associated with an increased islet blood perfusion.     

Hyperinsulinemia,hyperproinsulinemia and insulin resistance in the metabolic syndrome

For better comprehension of the metabolic syndrome, it is necessary to differentiate the effect of insulin on glucose metabolism on the one hand, and on other metabolic activities on the other hand. Whereas glucose utilization is affected by insulin resistance, the effect of insulin on lipid metabolism, ion and aminoacid transport does not seem to be diminished. Lipid metabolism, however, seems to play a crucial role in the induction of the vicious cycle. Increased energy and fat ingestion may be due to an increased number of galanin secreting cells in the hypothalamus. The excessive fat intake results in an increased rate of release of insulin and increased influx of triglycerides into the blood. From these triglycerides an excess of free fatty acids is released by the action of lipoprotein lipase. The increased plasma free fatty acid level then results in insulin resistance affecting glucose metabolism. Also, these free fatty acids may impair the secretion of insulin. Induction of insulin resistance results in higher glucose levels, which may cause hyperinsulinemia. Hyperinsulinemia maintains the elevation of triglycerides. When diabetes becomes overt and elevated glucose levels prevail, the hyperinsulinism acts on the metabolic pathways which are still sensitive to insulin, namely lipid metabolism, aminoacid transport and ion transport.     

Stimulation of glucagon and inhibition of insulin secretion evoked from carotid baroreceptors.

The influence from carotid baroreceptors on portal immuno-reactive glucagon and insulin levels and on arterial plasma glucose concentration was studied in vagotomized cats by sectioning of the sinus nerves. Such a complete elimination of the afferent baroreceptor discharge caused a prompt and pronounced increase in the glucose and glucagon levels, whereas the insulin concentration significantly decreased. The role of vascular barorecptors in the hyperglycemic response to hemorrhage is discussed.     

Stimulation of glucagon and inhibition of insulin secretion evoked from carotid baroreceptors

Summary The influence from carotid baroreceptors on portal immuno-reactive glucagon and insulin levels and on arterial plasma glucose concentration was studied in vagotomized cats by sectioning of the sinus nerves. Such a complete elimination of the afferent baroreceptor discharge caused a prompt and pronounced increase in the glucose and glucagon levels, whereas the insulin concentration significantly decreased. The role of vascular baroreceptors in the hyperglycemic response to hemorrhage is discussed.     

Änderungen des Elektrolytgehaltes von Erythrozyten und Plasma bei nephrektomierten Ratten

Summary After two-stage nephrectomy in rats the potassium concentration in the red blood corpuscles (RBC) decreases from 10.6 ± 0.3 to 5.5 ± 0.3 mEq per 100 ml of RBC within 48 h. The decrease is accompanied by a much smaller increase in the plasma potassium concentration; the hyperkaliemia in nephrectomized rats is less pronounced than in nephrectomized dogs or anuric humans. Na⁺ in RBC increases by about 44% after nephrectomy; while there is only a very slight decrease of Na⁺ in plasma. Plasma chlorides drop from 10.92 ± 0.08 mEq/100 ml of plasma to 6.00 ± 0.81 mEq % within 48 h after nephrectomy. RBC chlorides tend to increase again after an initial drop from 5.22 ± 0.07 to 3.82 ± 0.90 mEq% within the first 8 h.     

Influence of light on the plasma gonadotropin concentrations in the newborn rat.

The physiological increase in plasma gonadotropin (LH and FSH) levels in newborn rats is indisputably influenced by light. Permanent illumination accentuates this increase, whereas darkness decreases it in 16-day-old female rats. In male rats of the same age, only permanent illumination was tested with the same results.     

Effect of a restricted diet on the in vitro glucose-induced insulin release of aging rats.

To study the effect of a sudden loss of body weight on the beta-cell function of aging rats, basal and glucose-induced insulin secretion was measured in pancreatic islets obtained from young (2-month-old), adult (12-month-old) and aging (24-month-old) rats, either fed ad libitum or fed a restricted diet (50% caloric restriction). Basal insulin secretion was similar in islets of young, adult and older rats. Glucose stimulated insulin release was significantly reduced in aging rats as compared to young animals. Animals fed a restricted diet showed a prolonged and higher secretory rate during first phase release when compared to animals fed ad libitum.     

The effect of cyproheptadine on insulin biosynthesis

Summary The effect of a potent antiserotonin-antithistaminic compound, cyproheptadine (CPH) on insulin biosynthesis was studied in pancreatic islets isolated from CPH-treated rats. Though insulin content of islets was markedly reduced in CPH-treated rats, the incorporation of radiolabeled leucine into proinsulin and insulin fractions was not affected with respect to the rate and amount. It is concluded that CPH may deplete insulin content of the islets through causing the leakage of insulin.     

Components of biological,including seasonal,variation in hematological measurements and plasma fibrinogen concentrations in normal humans

This study has been carried out in order to examine the components of biologicalaand, in particular, seasonal variation in hematologic measurements in normal humans. Toward this end, 26 normal volunteers had monthly blood samplings during one calendar year for determination of number of red blood cells (RBC) and platelets, hemoglobin (Hb), hematocrit (Ht), mean corpuscular volume (MCV), MC Hb (MCH), MC Hb concentration (MCHC), RBC distribution width (RDW), mean platelet volume (MPV), platelet distribution width (PDW), plateletcrit (PCT), and plasma fibrinogen concentrations. The data were analyzed by means of spectral analyses of a group of time series or a single time series, and by means of repeated measures analyses of variance. Most of the hematologic variables show seasonal rhythms, such as annual rhythms or harmonics, which are expressed as a group phenomenon. An important part of the variance (>15%) in Ht, MCV, MCH, MCHC, RDW, number of platelets, MPV and plasma fibrinogen was explained by a yearly variation. The peak-trough differences (expressed as a percentage of the mean) in the yearly variations in number of RBC, Ht, MCV, MCH, MCHC and RDW were very low (all<8.5%). Number of platelets (14.4%) and plasma fibrinogen values (28%) showed a high-amplitude yearly variation. All hematological variables, except MCHC, show a high interindividual variability which exceeds by far the intraindividual variability.     

The effect of cyproheptadine on insulin biosynthesis

The effect of a potent antiserotonin-antihistaminic compound, cyproheptadine (CPH) on insulin biosynthesis was studied in pancreatic islets isolated from CPH-treated rats. Though insulin content of islets was markedly reduced in CPH-treated rats, the incorporation of radiolabeled leucine into proinsulin and insulin fractions was not affected with respect to the rate and amount. It is concluded that CPH may deplete insulin content of the islets through causing the leakage of insulin.     

Impaired insulin release in aging rats: Metabolic and ionic events

We investigated the effect of aging on glucose uptake, glucose-induced O₂ consumption, glucose-induced⁴⁵Ca movements, and calmodulin content to elucidate age-related impairment of glucose-induced insulin release in pancreatic islets of Wistar rats. Intact pancreatic islets from old (24-month-old) rats showed impaired glucose-induced insulin release; glucose uptake and O₂ consumption were lower in old than in young (2-month-old) or adult (12-month-old) rats. Moreover,⁴⁵Ca uptake and calmodulin content were decreased in pancreatic islets from older rats, which explained the impairment in glucose-induced insulin release in aging. No major differences between the 3 age groups in glucose-induced⁴⁵Ca efflux in pancreatic islets were observed.     

Effect of a restricted diet on the in vitro glucose-induced insulin release of aging rats

To study the effect of a sudden loss of body weight on the -cell function of aging rats, basal and glucose-induced insulin secretion was measured in pancreatic islets obtained from young (2-month-old), adult (12-month-old) and aging (24-month-old) rats, either fed ad libitum or fed a restricted diet (50% caloric restriction). Basal insulin secretion was similar in islets of young, adult and older rats. Glucose stimulated insulin release was significantly reduced in aging rats as compared to young animals. Animals fed a restricted diet showed a prolonged and higher secretory rate during first phase release when compared to animals fed ad libitum.