Decrease In Plasma Ca Research Articles

Can atrazine loaded nanocapsules reduce the toxic effects of this herbicide on the fish Prochilodus lineatus? A multibiomarker approach

Atrazine (ATZ) is a widely used herbicide that has the potential to contaminate the environment and cause deleterious effects on non-target organisms. Release systems for ATZ have been developed to minimize this contamination, such as nanocapsules prepared with poly (ε-caprolactone) (PCL). The objective of this work was to investigate the effects of nanoencapsulated ATZ compared to ATZ on biomarkers of the freshwater teleost Prochilodus lineatus. The fish were exposed for 24 and 96 h to nanoencapsulated ATZ (nATZ) and atrazine (ATZ) at concentrations of 2 and 20 μg L−1, just to the PCL nanocapsules without the herbicide (NANO) in the corresponding amounts or only to dechlorinated water (CTR). The results showed that nATZ was less toxic compared to ATZ, as it did not promote an increase in glycemia, alterations in antioxidants, nor in carbonic anhydrase enzyme activity, and no increase in the frequency of micronuclei and other nuclear erythrocyte abnormalities either. However, exposure to nATZ, as well as to ATZ and PCL nanocapsules, resulted in a reduction in hemoglobin content, increase in erythrocyte DNA damage, as well as changes in Ca2+-ATPase activity, leading to a decrease in plasma Ca+2. The Integrated Biomarker Response Index (IBR) depicted that exposure to ATZ promoted changes in a greater number of biomarkers compared to nATZ, indicating that the nanoencapsulation of the herbicide protected the animal from the effects of ATZ.

Nigella Sativa reverses osteoporosis in ovariectomized rats

BackgroundOsteoporosis poses a significant public health issue. It is a skeletal disorder characterized by compromised bone strength that predisposes to increased risk of fracture. There is a direct relationship between the lack of estrogen after menopause and the development of osteoporosis. About 33% of women over 50 will experience bone fractures as a result of osteoporosis. Nigella Sativa (NS) has been shown to have beneficial effects on bone and joint diseases. The present study was conducted to elucidate the protective effect of Nigella Sativa on osteoporosis produced by ovariectomy in rats.MethodsFemale Wistar rats aged 12–14 months were divided into three groups: sham-operated control (SHAM), ovariectomized (OVX), and ovariectomized supplemented with nigella sativa (OVX-NS) orally for 12 weeks; 4 weeks before ovariectomy and 8 weeks after. After 12 weeks, plasma levels of calcium (Ca+2), phosphorous (Pi), alkaline phosphatase (ALP), amino terminal collagen type 1 telopeptide, malondialdehyde (MDA), nitrates, nitric oxide surrogate, tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) were measured. Histological examination of the liver and the tibia was conducted. Histomorphometric analysis of the tibia was also performed.ResultsOVX rats showed significant decrease in plasma Ca+2, accompanied by a significant increase in plasma ALP, amino terminal collagen type 1 telopeptide, MDA, nitrates, TNF-α and IL-6. These changes were reversed by NS supplementation in OVX-NS group to be near SHAM levels. Histological examination of the tibias revealed discontinuous eroded bone trabeculae with widened bone marrow spaces in OVX rats accompanied by a significant decrease in both cortical and trabecular bone thickness compared to Sham rats. These parameters were markedly reversed in OVX-NS rats. Histological examination of the liver showed mononuclear cellular infiltration and congestion of blood vessels at the portal area in OVX rats which were not found in OVX-NS rats.ConclusionNigella sativa reverses osteoporosis in ovariectomized rats, which could be attributed to its high content of unsaturated fatty acids as well as its antioxidant and anti-inflammatory properties.

Calcimimetic NPS R-568 induces hypotensive effect in spontaneously hypertensive rats

The discovery of calcium receptors and calcimimetics created the possibility of "pharmacologic parathyroidectomy" (phPTX), which decreased secretion of parathormone (PTH). Parathyroid glands of spontaneously hypertensive rats (SHR) and of patients with primary hyperparathyroidism and hypertension secrete parathyroid hypertensive factor (PHF). Parathyroidectomy decreases blood pressure in these rats and in patients. The present study determined whether phPTX induced by calcimimetics decreases mean arterial blood pressure (MAP) in hypertensive rats. Hypertensive SHR and normotensive Wistar Kyoto (WKY) rats were used. Clearance experiments were performed and the effect of 1 mg/kg body weight (given intravenously) synthesized NPS R-568 (NPS) on MAP in the presence or absence of thyroparathyroidectomy (TPTX) was monitored. The success phPTX and TPTX were proven by a significant decrease in plasma Ca(2+) concentration and a decrease in urinary fractional phosphate excretion (FE Pi). The administration of NPS significantly decreased blood pressure in SHR versus SHR/control: Delta(0-50 min of experiment) MAP -16.5 +/- 2.5 mm Hg v -3.2 +/- 1.5 mm Hg (P < .002). The TPTX decreased blood pressure in SHR versus SHR/control and was not different versus SHR/TPTX/NPS (DeltaMAP: -10.2 +/- 1.6 mm Hg v -3.2 +/- 1.5 mm Hg (P < .01) and v -8.3 +/- 2.2 mm Hg (P = not significant). In normotensive WKY rats application of NPS did not reach significance in DeltaMAP: -6.7 +/- 1.8 mm Hg v -2.6 +/- 2.8 mm Hg (P = not significant) in WKY/control. The TPTX lowered blood pressure in WKY versus WKY/control and remained unchanged versus WKY/TPTX/NPS (DeltaMAP: -11.3 +/- 1.7 mm Hg v -2.6 +/- 2.8 mm Hg (P < .04) and v -11.4 +/- 2.6 mm Hg (P = not significant). We conclude that phPTX with NPS R-568 is responsible for a decrease of MAP in SHR.

Effects of alendronate on plasma calcium levels, urinary calcium excretion, and bone resorption markers in normal rats: comparison with elcatonin, synthetic eel calcitonin.

In normal rats given alendronate (0.01-6.25 mg/kg) or elcatonin (synthetic eel calcitonin; 0.32-8.0 U/kg), changes in urinary calcium (Ca), pyridinoline (Pyr), and deoxypyridinoline (D-Pyr) excretion during the hypocalcemic response were assessed. Although the lower doses (0.01-0.25 mg/kg) of alendronate did not influence plasma Ca, the high doses (1.25-6.25 mg/kg) significantly decreased plasma Ca by the third day after single iv administration. In these groups, urinary Ca excretion did not show any significant change, but urinary Pyr and D-Pyr excretion decreased significantly at high doses. The hypocalcemic effect lasted for only 1 or 2 days (2-3 days after injection) even at high doses of alendronate. In the group receiving elcatonin (8.0 U/kg, twice daily), a significant decrease in plasma Ca was evident as early as 1 day after the start of administration. This was accompanied by a marked increase in urinary Ca excretion in the early stage without a significant decrease in urinary Pyr or D-Pyr excretion, and the suppression of bone resorption was more pronounced in the late phase of treatment with elcatonin. These results suggest that alendronate decreases plasma Ca chiefly by suppressing bone resorption, whereas elcatonin decreases plasma Ca by inhibiting bone resorption and accelerating Ca excretion. The present data show that both alendronate and elcatonin inhibit bone resorption and exert an antihypercalcemic effect, but the mechanism of action is different in the two drugs.

Plasma osteocalcin concentrations in cows around parturition. The influence of a regular versus a very short dry period.

Plasma Ca, P, Mg and OC concentrations were compared between 2 groups of Holstein cows around 2nd calving. Thirteen cows were milked until their daily milk production was lower than 2 kg, which occurred 4 d before parturition. The control group (8 cows) was normally dried 8 weeks before the expected time of calving. Apart from the week following the initiation of the dry period where plasma OC concentrations were significantly lower in dried cows than in the control group (which would indicate lower bone remodeling in dried cows), no significant difference concerning Ca, P, Mg and OC concentrations were observed between the 2 groups of cows. This indicates that the only lack of 1 8-week-long dry period probably has no major immediate effect upon Ca and bone metabolism in young dairy cows given a convenient Ca and P daily intake. Nevertheless, the lack of the dried period might protect the cow against parturient hypocalcemia: the decrease in plasma Ca and P concentrations observed 12 h after calving was less intense in non-dried cows than in controls.

Changes in renal function of the chicken associated with calcitonin and parathyroid hormone

We have studied the effects of bovine parathyroid hormone (PTH) and salmon calcitonin (CT) on plasma calcium (Ca) and phosphate levels and on renal function in intact and parathyroidectomized (PTX) chickens, using a simple technique that separates urine from feces. In immature males and egg-laying females, the intravenous injection of PTH (10–20 IU/kg body wt) caused a transient fall in plasma Ca and phosphate levels, which was followed by an increase to a maximal level 20–30 min after the injection. By contrast, adult cockerels seldom showed any variation in plasma Ca or phosphate levels. In all birds, treatment with PTH increased glomerular filtration rate, urine flow rate, phosphate clearance, and Ca clearance, although this peaked later and remained elevated longer than did the phosphate clearance. The infusion of CT (1–20 U/kg over 30 min) caused a significant decrease in plasma Ca only in PTX or partially PTX chickens. All birds showed an increased GFR, urine volume, and urinary Ca excretion. In parathyroid-intact birds, the renal clearance of phosphate also increased, but peaked later and remained high longer than did Ca clearance, suggesting an increased endogenous PTH secretion. We conclude that plasma Ca and phosphate homeostasis in the chicken, as in the mammal, depends on a balanced release of PTH and CT. However, in the chicken, the response time is faster, thus minimizing the fluctuations in plasma Ca and phosphate levels resulting from exogenous hormone administration. This rapid homeostatic response is less effective when Ca demands by the body are high as in the growing or laying bird.

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

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.

Interrelationship of parathyroid and adrenocortical function in calcium homeostasis in the rat.

This study evaluated the relationship between the parathyroid glands (PTG) and the adrenal cortex in calcium (Ca) homeostasis in the rat. Adrenalectomy (AdX) alone caused no change in plasma Ca. Thyroparathyroidectomy (TX-PTX) caused a decrease in plasma Ca within 4 hr. Concomitant AdX prevented this decrease. Cortisol 5 (img/100 g body wt SC immediately after surgery) caused a decrease in plasma Ca of TX-PTX plus AdX rats, but not of intact rats. Parathyroid extract (PTE) (single injection of 100 U/100 g body wt SC) caused less increase of plasma Ca in intact rats than i n AdX rats. PTE (125 U/100 g body wt SC twice daily for 2 days) to intact rats caused an increase in plasma Ca, adrenocortical hyperplasia and increase in plasma corticosterone. Cortisone acetate (10 mg SC twice daily for 7 days) to intact rats caused PTG hyperplasia and increase in serum immunoreactive parathyroid hormone (iPTH), but with no change in plasma Ca. The results show that a) PTH-induced hypercalcemia leads to increased adren...

Magnesium, calcium, and phosphate excretion during osmotic diuresis in the dog.

Abstract Excretion rates and plasma concentrations of Ca, Na, Cl, and urea and excretion rates of PO 4 were measured in chloralose-anesthetized dogs subjected to various combinations of urea, hypertonic saline, and water loading. Osmotic diuresis, considered alone, had little influence on the excretion or clearance of Mg, Ca, or PO 4 . The clearance (or excretion) of Mg and Ca, but not PO 4 , was positively correlated with Na or Cl excretion. The slopes of the regressions of C Mg /liter of GFR and of C Ca /liter of GFR on VU Na /liter of GFR yielded values of approximately 3.0 and 3.2, respectively, at divalent ion excretion fractions below 10 per cent. Above this value, as observed during combined hypertonic saline and urea loading, the slopes were 6.2 and 5.7, respectively. Mannitol diuresis did not differ significantly from urea. Divalent ion clearances during mercurial diuresis were much greater, as related to Na or Cl excretion, than those observed during osmotic diuresis, suggesting specific mercurial depression of divalent ion transport. Anesthesia was associated with an increase in plasma PO 4 , a slight decrease in plasma Ca, and a moderate decrease in plasma Mg. The decrease in plasma Mg was intensified by urea loading but suppressed by hypertonic saline loading.