Jugular Venous Blood Samples Research Articles

Relationship between LH, FSH, and prolactin concentration and the secretion of androgens and estrogens by the preovulatory follicle in the ewe.

The ovarian secretion of estradiol, androstenedione, testosterone, and progesterone and the concentration of LH, FSH, and prolactin were measured in the periovulatory period of five ewes with ovarian or utero-ovarian autotransplants. Samples of jugular and ovarian venous blood were collected every 1 or 2 h before and for 96 h after induction of luteal regression on Day 10 of the cycle by injection of 100 µg cloprostenol. Progesterone concentration in jugular vein plasma fell to less than 1 ng/ml in all ewes by 24 h, and coincidental to this decline there was a significant increase in the secretion of LH and prolactin and an associated rise in the ovarian venous concentration of estradiol, testosterone, and androstenedione. The rise in LH secretion was associated with a twofold increase in the frequency of episodic pulses each of which stimulated an increase in the secretion of estradiol. In contrast the concentration of FSH declined significantly in the 48 h after luteal regression. Shortly after the onset of estrus (48 ± 2.5 h), there was a marked rise in the concentration of prolactin, FSH, and LH which reached a peak at 61 ± 4 h. At the start of this preovulating LH surge, there was a further substantial stimulation in the secretion of estradiol, testosterone, and androstenedione, followed by a sharp fall within 3, 5, and 7 h, respectively. In the 24 h after the preovulatory surge, there was a marked decline in the concentration of LH and prolactin as well as all ovarian steroids. However, within 12 h there was a further rise in the concentration of FSH which reached a second peak at 23 h after the LH peak. These results suggest that the increased secretion of estradiol from the preovulatory follicle is due to stimulation by episodic pulses of LH which occur with increased frequency as the concentration of progesterone falls during luteal regression. The sustained rise in LH which occurs during the preovulatory surge stimulates and then markedly inhibits aromatase activity and eventually all steroid secretion from the follicle. Thus the final stages of development of the preovulatory follicle are determined not by FSH but by the pattern of secretion of LH.

Short-term relationships between plasma LH, FSH and progesterone concentrations in post-partum dairy cows and the effect of Gn-RH injection.

Jugular venous blood samples were obtained from 7 dairy cows every 10 min for 10-19 h during the early- or mid-luteal phase of the oestrous cycle, and each cow was given 1 or 2 i.v. injections of 100 micrograms synthetic Gn-RH. Four of these cows were also sampled in a different cycle with no treatment being administered. Peaks of plasma LH, FHS and progesterone were detected in each animal in the absence of treatment; those of LH and progesterone often occurred in parallel. Injection of Gn-RH was always followed by a significant increase in plasma LH and progesterone concentrations and in most cases by a significant FSH increase. There was a significant temporal relationship between the peaks of all 3 hormones. A further 8 cows were sampled during the first 10 days post partum when the mean plasma progesterone concentration was low. An i.v. injection of 200 micrograms synthetic Gn-RH was given to each animal and this resulted in a significant increase in plasma LH and FSH concentrations, but in only one cow was the Gn-RH injection followed by a significant increase in plasma progesterone concentration. The LH response to Gn-RH injection was significantly less in cows injected on or before Day 5 post partum than in cows injected on Days 7-10 post partum.

Glucose and urea kinetics in cows in early lactation.

1. Four mature Friesian cows were used. For 2 weeks after calving they were fed 3 kg hay (147 g crude protein (nitrogen X 6.25; CP)/kg dry matter (DM) plus 9 kg concentrates (177 g CP/kg DM) per d and thereafter 4 kg hay plus 12 kg concentrates/d. 2. At approximately the 2nd, 4th and 9th weeks post-partum each cow was given a single intravenous dose of [14C]urea (1 mCi) and [6-3H]glucose (1.5 mCi). Following this, jugular venous blood samples were withdrawn up to 26 h post-injection. 3. The log (specific activity) v. time curves were not linear for either metabolite. Glucose irrversible loss rates (IRL) were calculated by a stochastic procedure. The linear part of the urea log (specific activity) v. time curve gave the same estimate for urea IRL rate as a stochastic method of calculation, but urea pool sizes were overestimated so that stochastic analysis of results was preferred. 4. Mean milk yields at the time of the three measurements were 27.1, 30.8 and 27.9 kg milk/d. 5. Urea IRL was significantly lower (P < 0.05) in the first 4 weeks of lactation than in the 9th, and blood urea concentration was lower (P < 0.05) in the 4th than in the 2nd and 9th week, but there was no close correlation between urea IRL and concentrations. 6. Glucose IRL rose (P < 0.05) between the 2nd and 9th weeks post-partum, perhaps due to the increase in feed intake. The results were generally consistent with the relationship between milk yield and glucose IRL established by Paterson & Linzell (1974). 7. Urea IRL (y) and milk protein-N (x) production values were used to calculate the efficiency of protein utilization (EPU) as x divided by (x+0.35 y). This assumes that 0.35 of urea IRL was due to protein catabolism. EPU was found to be 0.59-0.80 (mean 0.69). 8. The possible contribution of catabolized amino acids to glucose IRL was calculated by assuming that 0.35 of urea IRL was due to protein catabolism and 0.2 of catabolized protein-C passed through the glucose pool. On this basis the contribution of protein-C top glucose-C was < 25 g/kg glucose IRL.

The pH/Log PCO2 Buffer Curve of Horse Blood

Samples of jugular venous blood from six horses were equilibrated with six oxygen and carbon dioxide gas mixtures of PCO 2 between 28 and 54 mm Hg. In all six samples the correlations between the pH and the log PCO 2 values were linear and highly significant, with r in all six samples greater than 0.985. It was concluded that the Astrup method for the determination of the acid-base status of the blood of horses is valid.

Effects of dexamethasone on leukocyte counts in pregnant sheep and fetal lambs

In adult nonpregnant animals and human beings, glucocorticosteroids increase circulating leukocytes (predominantly neutrophils) and decrease lymphocytes, monocytes, and eosinophils. We were interested in studying effects of glucocorticoids on leukocyte counts during pregnancy to determine any differences between responses in the nonpregnant and pregnant states. After general anesthesia was administered, we placed catheters in a carotid artery and a jugular vein in pregnant sheep and in fetal lambs. Six days after surgery, we administered dexamethasone intravenously to the mother (0.2 mg. per kilogram) or to the fetus (0.06 mg. per kilogram) and obtained maternal and fetal jugular venous blood samples immediately before (control) and 3, 6, 12, 24, 48, and 72 hours after steroid injection. administration of dexamethasone to the mother significantly increased total leukocyte and neutrophil counts (leukocytes per cubic millimeter blood) and decreased lymphocyte and eosinophil counts, but it did not change monocyte counts. Leukocyte counts returmed to control values within 48 hours. Administration of dexamsthasone to the fetus rapidly increased total leukocyte and neutrophil counts, decreased monocyte and eosinophil counts, and had no effect on lymphocyte counts. Fetal leukocyte counts returned to control values by 24 hours after dexamethasone injection. Our results suggest that maternal and fetal leukocytes can respond to glucocorticoids as they do in the adult nonpregnant state.

Treatment of chronic post partum endometritis in cattle with cloprostenol.

Seven dairy cattle showing clinical post partum endometritis were monitored daily by rectal examination of uterus, ovaries and vagina and by sampling of jugular venous blood and uterine pus. The animals were treated by intramuscular injection of 500 microgram cloprostenol (ICI). All seven animals had an immediate reduction of plasma progesterone concentrations and showed oestrus within two to three days. In six cases the clinical endometritis resolved, with uterine involution, within seven days and uterine mucus sample showed no specific growth. One animal required a second cloprostenol injection 11 days after the first to achieve complete resolution. Subsequently, plasma progesterone levels rose in all animals but two cases later appeared to become anoestrous, perhaps due to pituitary insufficiency. In a further study of chronic endometritis in cattle in the field, 51 out of 56 animals treated in the presence of a corpus luteum showed oestrus within 14 days with resolution of the condition; five others did not respond. None of the three cases which had been treated in the absence of a corpus luteum showed any improvement. This lack of response was not unexpected and supports the view that the mode of action of cloprostenol in this treatment regime is to induce luteolysis. The mechanism of therapy and possible explanation for the occurrence of chronic endometritis are discussed.

Sheep lactate entry-rate measurements: error due to sampling jugular blood.

Carotid arterial and jugular venous blood samples were taken simultaneously during primed continuous infusions of L-[U-14C]lactate in four sheep. The mean rate (n = 4) of total net formation of lactate (0.394 +/- 0.047 mg C/min per kg) calculated from the results obtained by analyzing the jugular blood samples for lactate concentration and specific radioactivity was significantly higher (0.01 greater than P greater than 0.005) than the mean rate (n = 4) calculated from the results of analysis of the arterial samples (0.302 +/- 0.036 mg C/min per kg). The error in the estimation of the rate of total net formation of lactate due to jugular sampling resulted from the negative arteriovenous difference found for lactate across the tissues of the head. These results illustrate the general need for examination of the suitability of venous sampling in experiments that make use of the continuous infusion isotope-dilution method.

Uptake of individual amino acids by the human brain.

SummaryIndividual plasma amino acids were determined in simultaneously drawn arterial and jugular venous blood samples obtained from healthy postabsorptive subjects. Consistently positive A-V differences were observed for virtually all amino acids, indicating a net uptake of essential and nonessential amino acids by the brain in intact man.The authors are grateful to Chester Meyers for skillful technical assistance.

Progesterone concentration in the peripheral plasma of pregnant goats.

SUMMARY Plasma progesterone concentration was measured by a competitive protein-binding method in serial samples of jugular venous blood from 21 pregnant goats, 11 with twin and 10 with single foetuses. Progesterone levels in twin pregnancies were significantly greater than in singletons. The mean progesterone concentration (ng/ml plasma) in the twin pregnancies was greatest during the 3rd month of gestation (10·7 ± 0·4 (s.e.m.)) and in the singletons during the 4th month (7·8 ± 0·2 (s.e.m.)). There was a significant decrease in mean progesterone concentration in the last month of pregnancy due to a steady decline in the last 7 days before parturition. The mean progesterone concentrations at parturition in five twin and eight single pregnancies were 2·2 ± 0·4 and 1·5 ± 0·2 (s.e.m.) ng/ml plasma respectively; there was no significant difference between these values. In cord blood from nine kids immediately after delivery the progesterone concentration was 0·9 ± 0·1 ng/ml.

Determination of the energy expenditure of penned and grazing sheep from estimates of carbon dioxide entry rate.

1. NaH14CO3, was infused at a constant rate either subcutaneously or intraperitoneally into sheep kept in a uniform environment and consuming a standard amount of food each hour. After 3 h of infusion the specific radioactivity (SR) of COe obtained by acidification of samples of blood taken from the right atrium showed no significant change with time until after 22 h when the infusions were stopped.2. Entry rates of COa (I/h) in sheep were estimated from the ratio of rate of infusion of14CO2, as NaH14C08(µCi/h) to the SR of CO2(µCi/l) in samples of jugular venous blood, urine and exhaled gas taken after infusions had been in progress for at least 3 h. Concurrently, rates of energy expenditure were calculated from the gaseous exchanges over periods of 60–90 min which were determined for grazing sheep by use of re-entrant tracheal cannulation and meter-ing and analysis of exhaled gas, or for housed sheep by measurement in respiration chambers.3. Significant positive relationships were found between entry rate, the independent variable, and the contemporary energy expenditure. Equations obtained for grazing sheep were not significantly different from those obtained for other, housed, sheep when both groups were infused subcutaneously and COz for assay of radioactivity was obtained in all instances from blood, or in all instances from urine.4. With subcutaneous infusion the equation relating energy expenditure to entry rate estimated from the SR of urinary COa differed significantly from that where entry rate was derived from radioactivity assays of blood or exhaled CO2. There was also a significant differ-ence between two equations where entry rates were determined from the SR of blood CO2but route of infusion was in the one instance intravenous and in the other was sub-cutaneous. Reasons for the differences between equations are discussed.5. Changes in the rates of energy expenditure of sheep effected by intermittent exercise on a treadmill were reflected in changes in CO2entry rates. Values for the energy cost of hori-zontal locomotion by the sheep were derived from the entry rates and were similar in magni-tude to those reported by other workers.6. I t is suggested that the method of determining energy expenditure from COz entry rate may be adapted for use on many species of animal in a variety of environments.

Cerebrospinal fluid metabolic acidosis and brain oxygen supply. Studies in patients with brain infarction.

During the first 12 days after suffering acute ischemic strokes, lumbar cerebrospinal fluid (CSF), arterial, and jugular venous blood samples of 102 patients were analyzed for acid-base and gas values. Significantly increased CSF lactate and pyruvate concentrations with correspondingly decreased bicarbonate ion levels were the most characteristic findings. Respiratory alkalosis and hypoxemia of arterial and cerebral venous blood were also common. Frequently, a supernormal jugular venous oxygen pressure was recorded. The majority of these patients had a more elevated CSF lactate concentration; the patients with pronounced cerebral venous hypoxemia had a smaller increase of CSF lactate level. Disturbances of brain acid-base status may be important in the regulation of cerebral blood flow and oxygen supply in patients with ischemic strokes.

An afferent pathway for the selective release of vasopressin in response to carotid occlusion and haemorrhage in the cat.

1. The release of neurohypophysial hormones in response to carotid occlusion and haemorrhage has been studied in anaesthetized cats. Samples of jugular venous blood were extracted with alcohol and the extracts assayed for antidiuretic and milk-ejecting activity.2. The release of vasopressin in response to bilateral occlusion of the common carotid arteries has been confirmed in the cat; this effect was abolished when the sinus nerves were divided.3. Using a new sensitive preparation for the assay of milk-ejecting activity in blood extracts, it has been shown that no oxytocin accompanies the release of vasopressin during carotid occlusion.4. The independent release of vasopressin without oxytocin during haemorrhage has also been confirmed, and the role of the sinus nerves and vagi in this response investigated. Bilateral division of either nerve reduced the response, but the vagus appeared to be of greater importance than the sinus nerve.5. A reflex arc for the selective release of vasopressin has been proposed, of which the fibres of the sinus nerves and vagi form the afferent component and the neurones of the supraoptic nucleus the efferent component.