Episodic secretion of parathyroid hormone in the dog

1981 ◽  
Vol 241 (3) ◽  
pp. E171-E177
Author(s):  
J. Fox ◽  
K. P. Offord ◽  
H. Heath
Keyword(s):  
Spectral Analysis ◽  
Parathyroid Hormone ◽  
Conscious Dogs ◽  
Blood Samples ◽  
Pentobarbital Anesthesia ◽  
Ipth Concentration

This study was designed to determine whether parathyroid hormone (PTH) is secreted episodically, to characterize any such rhythms, and to see whether the rhythms can be altered by stimulating PTH secretion using constant hypocalcemia. We collected blood samples at 1-min intervals for 1 h from the precava or postcava of conscious dogs during normocalcemia or induced, constant hypocalcemia. In two anesthetized normocalcemic dogs we catheterized a caudal thyroid vein and collected all the effluent blood in 1-min fractions. Immunoreactive PTH (IPTH) concentrations were determined in quadruplicate, and the results were subjected to spectral analysis. In both the precava and postcava of normocalcemic dogs, there were regular oscillations in IPTH levels with a period of 12 min (range, 10–15 min) and a +/- 14% variation about the overall mean. Although significant two- to fourfold changes in IPTH levels still occurred during constant hypocalcemia, there was no significant rhythmicity. Significant cycles in IPTH concentration (mean 8.4-min period) were observed in thyroid venous effluent plasma during normocalcemia, confirming that the phenomenon represented episodic secretion that was not affected by pentobarbital anesthesia.

The “calcium clamp”: effect of constant hypocalcemia on parathyroid hormone secretion

1981 ◽  
Vol 240 (6) ◽  
pp. E649-E655
Author(s):  
J. Fox ◽  
H. Heath
Keyword(s):  
Parathyroid Hormone ◽  
Feedback Control ◽  
Rapid Determination ◽  
Hormone Secretion ◽  
Conscious Dogs ◽  
Half Time ◽  
Experimental Animals ◽  
A New Technique ◽  
Ipth Concentration

This report describes acute studies of parathyroid hormone (PTH) secretion and metabolism in conscious dogs, performed with a new technique, the “calcium clamp.” Bolus injections and graded infusions of either calcium (Ca) or EGTA, respectively, increase or decrease plasma Ca to desired levels in 1–2 min; rapid determination of plasma Ca permits feedback control of the infusion rates to maintain the desired Ca concentration for prolonged periods. Using this technique, we have examined the effect in five dogs of a sustained (1 h) decrease in plasma Ca from 9.6 to 7.6 mg/dl on the secretion of PTH. Plasma immunoreactive PTH (IPTH) concentration in precaval blood increased within 1 min, peaked at 4–10 min (greater than 5 times control), but thereafter declined gradually to 57% of the maximum at 60 min, despite ongoing and constant hypocalcemia. Abrupt restoration of normocalcemia caused IPTH levels to decrease with an apparent half-time of 3.0 +/- 0.3 min (mean +/- SE). Thus, external feedback-regulated control of plasma Ca is possible in experimental animals. IPTH concentrations decline from the maximum during constant hypocalcemia, a new observation that suggests that PTH secretion and/or metabolism are altered progressively by the hypocalcemia.

ADRENAL 17-HYDROXYCORTICOSTEROID SECRETION IN THE DOG IN RESPONSE TO ETHANOL

1972 ◽  
Vol 70 (4) ◽  
pp. 736-740 ◽  
Author(s):  
T. Suzuki ◽  
R. Higashi ◽  
T. Hirose ◽  
H. Ikeda ◽  
K. Tamura
Keyword(s):  
Venous Blood ◽  
Secretion Rate ◽  
Conscious Dogs ◽  
Blood Samples ◽  
Before And After

ABSTRACT Conscious dogs were infused intravenously with ethanol in doses of 0.7 and 1.0 g/kg. The adrenal venous blood samples were collected before and after the infusion of ethanol and analysed for 17-hydroxycorticosteroids (17-OHCS). After the infusion of 0.7 g/kg (subanaesthetic dose) of ethanol the adrenal 17-OHCS secretion rate showed either a slight increase or no change. After the infusion of 1.0 g/kg (anaesthetic dose) of ethanol the adrenal 17-OHCS secretion rate increased markedly and reached 1.21±0.15 (mean±sem) μg/kg/min, while it was 0.09±0.023 μg/kg/min before the infusion.

Vasopressin in blood and third ventricle CSF of dogs in chronic experiments

1983 ◽  
Vol 245 (4) ◽  
pp. R541-R548 ◽  
Author(s):  
C. Simon-Oppermann ◽  
D. Gray ◽  
E. Szczepanska-Sadowska ◽  
E. Simon
Keyword(s):  
Cerebrospinal Fluid ◽  
Arginine Vasopressin ◽  
Anterior Part ◽  
Third Ventricle ◽  
Conscious State ◽  
Conscious Dogs ◽  
Inhalation Anesthesia ◽  
Blood Samples ◽  
The Third ◽  
Device Implantation

A device for chronic implantation was developed that allowed sampling of cerebrospinal fluid (CSF) from the anterior part of the third cerebral ventricle (A3V) of dogs in repeated experiments for up to 4 mo. Osmolalities, electrolyte concentrations, and concentrations of arginine vasopressin (AVP) measured with a radioimmunoassay were determined in repeated experiments on the chronically prepared animals under conditions of normal hydration, both in the conscious state and during inhalation anesthesia. In conscious dogs, AVP concentrations in plasma and CSF were 3.3 +/- 0.4 and 21.8 +/- 2.5 pg X ml-1, respectively. During anesthesia without surgical interference, the AVP concentrations in plasma and CSF were increased twofold above the levels obtained in conscious dogs. During the time of observation (180 min) all measured parameters remained constant. The AVP concentrations in plasma and CSF samples collected during the surgical procedure of device implantation were about 10-fold higher than in the samples collected during the conscious state. Thus, in each experimental condition, AVP concentration in the CSF collected from the A3V was consistently higher than that in the simultaneously collected blood samples.

Pentobarbital anesthesia modifies pulmonary vasoregulation after hypoperfusion

1988 ◽  
Vol 255 (3) ◽  
pp. H569-H576
Author(s):  
B. B. Chen ◽  
D. P. Nyhan ◽  
H. M. Goll ◽  
P. W. Clougherty ◽  
D. M. Fehr ◽  
...  
Keyword(s):  
Cardiac Index ◽  
Adrenergic Receptor ◽  
Conscious State ◽  
Conscious Dogs ◽  
Mixed Venous Blood ◽  
Vascular Response ◽  
Beta Adrenergic ◽  
Pentobarbital Anesthesia ◽  
Pulmonary Vasoconstriction ◽  
Receptor Block

Our objectives were 1) to investigate the extent to which the pulmonary vascular response to increasing cardiac index after a period of hypotension and hypoperfusion (defined as reperfusion) measured in conscious dogs is altered during pentobarbital sodium anesthesia, and 2) to determine whether pentobarbital anesthesia modifies autonomic nervous system (ANS) regulation of the pulmonary circulation during reperfusion. Base-line and reperfusion pulmonary vascular pressure-cardiac index (P/Q) plots were generated by stepwise inflation and deflation, respectively, of an inferior vena caval occluder to vary Q in conscious and pentobarbital-anesthetized (30 mg/kg iv) dogs. During pentobarbital anesthesia, controlled ventilation (without positive end-expiratory pressure) allowed matching of systemic arterial and mixed venous blood gases to conscious values. Marked pulmonary vasoconstriction (P less than 0.01) was observed during reperfusion in pentobarbital-anesthetized but not in conscious dogs. Both sympathetic alpha-adrenergic receptor block and total ANS ganglionic block attenuated, but did not abolish, the pulmonary vasoconstriction during reperfusion in pentobarbital-anesthetized dogs. Neither sympathetic beta-adrenergic receptor block nor cholinergic receptor block enhanced the magnitude of the pulmonary vasoconstrictor response to reperfusion during pentobarbital anesthesia. Thus, in contrast to the conscious state, the pulmonary vascular response to reperfusion is characterized by active, non-flow-dependent pulmonary vasoconstriction during pentobarbital anesthesia. This response is primarily, but not exclusively, mediated by sympathetic alpha-adrenergic vasoconstriction and is not offset by either sympathetic beta-adrenergic or cholinergic vasodilation. These results indicate, that, compared with the conscious state, pentobarbital anesthesia modifies pulmonary vasoregulation, during reperfusion following hypotension and hypoperfusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Pentobarbital anesthesia alters pulmonary vascular response to neural antagonists

1989 ◽  
Vol 256 (5) ◽  
pp. H1384-H1392 ◽  
Author(s):  
D. P. Nyhan ◽  
H. M. Goll ◽  
B. B. Chen ◽  
D. M. Fehr ◽  
P. W. Clougherty ◽  
...  
Keyword(s):  
Adrenergic Receptor ◽  
Vena Cava ◽  
Cholinergic Receptor ◽  
Conscious Dogs ◽  
Base Line ◽  
Pentobarbital Anesthesia ◽  
Pulmonary Vasodilation ◽  
Receptor Block ◽  
Pentobarbital Sodium Anesthesia ◽  
Line P

We investigated the effects of pentobarbital sodium anesthesia on vasoregulation of the pulmonary circulation. Our specific objectives were to 1) assess the net effect of pentobarbital on the base-line pulmonary vascular pressure-to-cardiac index (P/Q) relationship compared with that measured in conscious dogs, and 2) determine whether autonomic nervous system (ANS) regulation of the intact P/Q relationship is altered during pentobarbital. P/Q plots were constructed by graded constriction of the thoracic inferior vena cava, which produced stepwise decreases in Q. Pentobarbital (30 mg/kg iv) had no net effect on the base-line P/Q relationship. In contrast, changes in the conscious intact P/Q relationship in response to ANS antagonists were markedly altered during pentobarbital. Sympathetic alpha-adrenergic receptor block with prazosin caused active pulmonary vasodilation (P less than 0.01) in conscious dogs but caused vasoconstriction (P less than 0.01) during pentobarbital. Sympathetic beta-adrenergic receptor block with propranolol caused active pulmonary vasoconstriction (P less than 0.01) in both groups, but the magnitude of the vasoconstriction was attenuated (P less than 0.05) during pentobarbital at most levels of Q. Finally, cholinergic receptor block with atropine resulted in active pulmonary vasodilation (P less than 0.01) in conscious dogs, whereas vasoconstriction (P less than 0.01) was observed during pentobarbital. Thus, although pentobarbital had no net effect on the base-line P/Q relationship measured in conscious dogs, ANS regulation of the intact pulmonary vascular P/Q relationship was altered during pentobarbital anesthesia.

scholarly journals Stability of Parathyroid Hormone-Related Protein and Parathyroid Hormone at Room Temperature

1994 ◽  
Vol 31 (5) ◽  
pp. 497-500 ◽  
Author(s):  
G E Levin ◽  
J A Nisbet
Keyword(s):  
Parathyroid Hormone ◽  
Protease Inhibitor ◽  
Room Temperature ◽  
Related Protein ◽  
Blood Samples ◽  
Parathyroid Hormone Related Protein ◽  
Edta Plasma ◽  
The Stability ◽  
Serum Pth ◽  
Zero Time

The stability of plasma parathyroid hormone-related protein (PTHrP) as measured by the Nichols Institute assay at room temperature was assessed over a period of 72 h in blood samples collected in protease inhibitor tubes and EDTA tubes at 0, 6, 24, 48 and 72 h from 10 patients with hypercalcaemia of malignancy. Mean plasma PTHrP concentrations in blood samples collected in protease inhibitor tubes remained stable for up to 48 h but had decreased by 10% at 72 h. The mean EDTA plasma PTHrP at zero time was 67% of the protease inhibitor tube value and this had fallen to 39% at 72 h. The stability of parathyroid hormone (PTH) in separated blood samples was also assessed by collection into heparin and plain tubes as well as EDTA and protease inhibitor tubes. Serum PTH concentrations progressively declined throughout the 72 h study period although the zero time values were significantly higher than corresponding plasma PTH concentrations. Plasma PTH concentrations appeared to be stable when blood was collected in heparin, EDTA and protease inhibitor tubes during the 72 h period, except in one subject with markedly elevated plasma amylase activity.

scholarly journals Large carboxy-terminal parathyroid hormone (PTH) fragment with a relatively longer half-life than 1-84 PTH is secreted directly from the parathyroid gland in humans

2003 ◽  
pp. 301-306 ◽  
Author(s):  
H Yamashita ◽  
P Gao ◽  
T Cantor ◽  
T Futata ◽  
T Murakami ◽  
...  
Keyword(s):  
Parathyroid Hormone ◽  
Parathyroid Gland ◽  
Half Life ◽  
Contralateral Side ◽  
Study Group ◽  
Blood Samples ◽  
Glandular Secretion ◽  
Whole Pth ◽  
Ultrasonographic Guidance ◽  
Carboxy Terminal

OBJECTIVE: It was discovered that an immunoreactive large carboxy-terminal parathyroid hormone (PTH) fragment (large C-PTH), likely 7-84 PTH, is present in the circulation. However, very little is known about the production and metabolism of this large C-PTH. Combining a whole molecule PTH (whole PTH) immunoradiometric assay (IRMA) specifically for 1-84 PTH and an intact PTH (iPTH) IRMA for the sum of 1-84 PTH and large C-PTH, we were able to assess the circulating level of this large C-PTH as well as the glandular secretion and metabolism of this large C-PTH in primary hyperparathyroidism (pHPT). METHODS: This study consisted of two patient groups consisting of 77 pHPT patients with a single adenoma. Of these, 43 comprised the venous sampling study group and 70 comprised the intra-operative PTH study group. (Seven patients belonged only to the former group, 34 patients to only the latter group, and 36 patients to both groups.) Preoperatively, blood samples were drawn from the bilateral internal jugular vein by ultrasonographic guidance and from the peripheral vein (n=43). During surgery, blood samples were drawn after anesthesia (basal level), before excision (pre-excision level) of one enlarged parathyroid gland, and at 5, 10, and 15 min post-excision (n=70). RESULTS: There were 26 patients whose iPTH assay levels differed by more than 10% between the right and left internal jugular. In 24 of the 26 patients, the large C-PTH levels obtained from the adenoma side were significantly higher than those from the contralateral side (117+/-135 vs 43+/-33 pg/ml, P<0.001). The plasma whole PTH values decreased more rapidly than the iPTH values after parathyroidectomy (P<0.001). CONCLUSIONS: Our study has demonstrated that the large C-PTH, likely 7-84 PTH, is directly released from the parathyroid gland in humans. Since the half-life of 1-84 PTH is much shorter than large C-PTH, likely 7-84 PTH, it would be advantageous to use an assay that specifically measures 1-84 PTH for intra-operative monitoring of parathyroidectomy.

scholarly journals Analytical Differences in Intraoperative Parathyroid Hormone Assays

2019 ◽  
Vol 3 (5) ◽  
pp. 788-798 ◽  
Author(s):  
Edward K Y Leung ◽  
Christine C Lee ◽  
Peter Angelos ◽  
Edwin L Kaplan ◽  
Raymon H Grogan ◽  
...  
Keyword(s):  
Parathyroid Hormone ◽  
Clinical Chemistry ◽  
Turnaround Time ◽  
Surgical Patients ◽  
Chemistry Laboratory ◽  
Blood Samples ◽  
Significant Difference ◽  
Clinical Chemistry Laboratory ◽  
Patient Series ◽  
Intraoperative Parathyroid Hormone

Abstract Background We compared the rates of intraoperative parathyroid hormone (PTH) decline using the Siemens Immulite® Turbo PTH and Roche Elecsys® short turnaround time PTH assays in 95 consecutive surgical patients to investigate analytical and turnaround time (TAT) differences between the tests performed in the operating room (OR) vs the central clinical chemistry laboratory (CCL). Methods Serial blood samples from 95 patients undergoing parathyroidectomy were collected and measured using the 2 immunoassays. Specimens from the first 15 patients were measured simultaneously in the OR and CCL and used for the TAT study. In addition to 2 baseline samples, specimens were collected at 5, 10, and 15 min (for some patients, &gt;15 min) after parathyroidectomy. Results In the TAT study, a significant difference was observed (OR median 20 min vs CCL median 27 min; P &lt; 0.05). Of the 95 patient series, slower rates of parathyroid hormone decrease were observed in approximately 20% of the patients when comparing the Roche with the Immulite immunoassay. Conclusions There was a slightly longer TAT in the CCL compared with running the assay directly within the OR (median difference of approximately 7 min). For a majority of the patients, both methods showed equivalent rates of PTH decline; however, for approximately 20% of the patients, there was a slower rate of PTH decline using the Roche assay.

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