Hematocrit as an index of changes in plasma volume in conscious dogs

Summary Hematocrit (HCT) measurements were made in intact and splenectomized conscious dogs to determine if observed decreases in HCT were produced by plasma volume expansion or splenic sequestration of erythrocytes. We found that in conscious dogs HCT is a poor indicator of changes in plasma volume.Supported by National Institutes of Health grant No. HL 13427.I.Z. ist the recipient of an Established Investigator Award from the American Heart Association.Acknowledgment. The authors wish to thank Mary Anne Richards for her technical assistance.     

Xenopsin stimulates exocrine pancreatic secretion in the dog

Summary The octapeptide xenopsin, previously isolated from amphibian skin, stimulates exocrine pancreatic secretion of bicarbonate and protein in conscious dogs and increases the volume of secretion. This effect is shown in the dose range of 1.25 up to 160 pmoles kg^–1min^–1 The high potency of this peptide is suggestive of a possible physiological role of xenopsin in mammals.This work was supported by the Deutsche Forschungsgemeinschaft Fe 127/4.     

Acute physiological responses during blood substitution with colloidal gelatin in conscious rats

The effects of exchange-transfusion with a proprietary gelatin-based plasma volume expander, Haemaccel, have been investigated in conscious, chronically-catheterized rats. No adverse changes in basic cardiovascular or respiratory functions occurred during the procedure although an increase in intravascular fluid sodium but not potassium concentration was observed.     

Acute physiological responses during blood substitution with colloidal gelatin in conscious rats

Summary The effects of exchange-transfusion with a proprietary gelatin-based plasma volume expander, Haemaccel, have been investigated in conscious, chronically-catheterized rats. No adverse changes in basic cardiovascular or respiratory functions occurred during the procedure although an increase in intravascular fluid sodium but not potassium concentration was observed.     

Gastric secretion during anaesthesia and its inhibition by metiamide and other drugs.

The histamine H2-receptor antagonist, metiamide, inhibits the acid gastric secretion produced by chloralose-urethane anaesthesia in dogs carrying gastric cannulae chronically. This secretion is also prevented by atropine and hexamethonium. "Spontaneous" gastric secretion of vagal origin in conscious dogs is also blocked by metiamide.     

Digoxin distribution between plasma and myocardium in hypoxic and non-hypoxic dogs

Summary The relationship between plasma and myocardial digoxin concentrations was investigated in hypoxic and nonhypoxic dogs. The results indicate that hypoxic dogs have lower plasma levels, higher myocardial levels, and an altered myocardial distribution when compared to non-hypoxic dogs.     

Presence of sodium transport inhibiting factor in dog plasma during volume expansion.

Plasma dialysates from volume-expanded dogs (E) were compared directly to dialysates from the same dogs when hydropenic. In a double-blind study, E caused relative inhibition of short-circuit current in toad urinary bladder. We therefore confirm the presence of a sodium transport inhibiting factor in plasma of volume-expanded dogs.     

Presence of sodium transport inhibiting factor in dog plasma during volume expansion

Summary Plasma dialysates from volume-expanded dogs (E) were compared directly to dialysates from the same dogs when hydropenic. In a double-blind study, E caused relative inhibition of short-circuit current in toad urinary bladder. We therefore confirm the presence of a sodium transport inhibiting factor in plasma of volume-expanded dogs.Acknowledgments. This study was supported by the Philadelphia Veterans Administration Hospital (103.6M). We would like to thank the laboratory of Dr V. Buckalew at Bowman Gray School of Medicine, Winston-Salem, North-Carolina, for preparation of plasma dialysates; G. Huber and E. Fink for technical assistance and K. Conrad for secretarial assistance.     

Independence of circulating insulin levels of the increased glucose turnover in shivering dogs

Summary In dogs, selective insulin deficiency induced by simultaneous somatostatin and glucagon infusion does not alter the high rate of glucose utilization provoked by acute cold exposure. However, both in resting and in shivering dogs, lowering of plasma insulin decreases plasma glucose metabolic clearance significantly.     

Independence of circulating insulin levels of the increased glucose turnover in shivering dogs

In dogs, selective insulin deficiency induced by simultaneous somatostatin and glucagon infusion does not alter the high rate of glucose utilization provoked by acute cold exposure. However, both in resting and in shivering dogs, lowering of plasma insulin decreases plasma glucose metabolic clearance significantly.     

Inhibitory effect of atropine on the isoprenaline-induced increase in vasopressin plasma concentration in rats

The isoprenaline-induced increase in plasma levels of vasopressin in conscious rats was reduced by intravenous and intracerebroventricular applications of atropine. It is concluded that central neurons with muscarinic receptors contribute to the isoprenaline-induced vasopressin release.     

Inhibitory effect of atropine on the isoprenaline-induced increase in vasopressin plasma concentration in rats

Summary The isoprenaline-induced increase in plasma levels of vasopressin in conscious rats was reduced by intravenous and intracerebroventricular applications of atropine. It is concluded that central neurons with muscarinic receptors contribute to the isoprenaline-induced vasopressin release.     

Hematocrit and hemoglobin concentration in four chromosomal species and some isolated populations of actively speciating subterranean mole rats in Israel

Hematocrit (HCT) and hemoglobin (Hb) concentration were measured in four chromosomal species and some peripherally semi-isolated and isolated populations of the mole rat superspecies Spalax ehrenbergi in Israel. HCT was 52.0, 51.4, 50.9, and 47.8%, and Hb was 16.0, 16.6, 16.3, and 14.7 g/100 ml for 2n = 52, 58, 54, and 60, respectively. The species 2n = 60, which lives in arid habitats, had lower HCT and Hb than the other three species. HCT decreased as aridity increased between the species and within the species 2n = 60. Changes in HCT probably reflect clinal changes in both soil permeability to gases and ambient temperature.     

Hematocrit and hemoglobin concentration in four chromosomal species and some isolated populations of actively speciating subterranean mole rats in Israel

Summary Hematocrit (HCT) and hemoglobin (Hb) concentration were measured in four chromosomal species and some peripherally semi-isolated and isolated populations of the mole rat superspeciesSpalax ehrenbergi in Israel. HCT was 52.0, 51.4, 50.9, and 47.8%, and Hb was 16.0, 16.6, 16.3, and 14.7 g/100 ml for 2n=52, 58, 54, and 60, respectively. The species 2n=60, which lives in arid habitats, had lower HCT and Hb than the other three species. HCT decreased as aridity increased between the species and within the species 2n=60. Changes in HCT probably reflect clinal changes in both soil permeability to gases and ambient temperature.     

Substance P and neurotensin: Opposite effects on plasma cholesterol levels in ovariectomized conscious rats

Summary Intravenous pulse injection of neurotensin produces a significant and dose-dependent increase in plasma cholesterol levels in ovariectomized conscious rats, whereas substance P has opposite effect. 4-Aminopyrazolo (3,4,-d) pyrimidine, (4-APP) also significantly lowers plasma cholesterol. The suppressive effects of both substance P and 4-APP were readily reversed by neurotensin, suggesting that the peptides act on hepatic lipoprotein secretion.Supported by grants from the Indian Council of Medical Research (ICMR), New Delhi. K.R. was recipient of a UGC fellowship.     

Effect of anaesthesia on growth hormone secretion in the domestic fowl (Gallus domesticus)

Summary Chloral hydrate, Equithesin, Althesin, Rompun, Sagatal and ether anaesthesia lowered the concentration of plasma growth hormone in immature cockerels. Handling and serial bleeding of the conscious controls had no effect on the growth hormone concentration.     

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 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.     

Changes in plasma enzyme concentrations in response to blood substitution with perfluorocarbon emulsion in the conscious rat

The effects of near total blood replacement with the proprietary perfluorocarbon (PFC)-based emulsion, Fluosol-DA 20%, on plasma concentrations of 2 enzymes, lactate dehydrogeanse (LDH) and alkaline phosphatase (ALP), have been examined in conscious, chronically catheterized rats. A pronounced fall in both plasma LDH (p less than 0.05) an ALP (p less than 0.01) occurred in response to exchange-transfusion. However, at 6 h following blood replacement, plasma concentrations of both enzymes had risen to values significantly greater than those measured immediately before perfusion. The observed changes in plasma LDH and ALP after blood replacement with Fluosol-DA indicated alterations in normal functioning of tissues from which these enzymes originate.