Expression of Arginine Vasopressin Type 2 Receptor in Canine Mammary Tumours: Preliminary Results.

The aims of this study were to investigate the potential association of arginine vasopressin type 2 receptor (AVPR2) in canine mammary tumours with expression of oestrogen receptors α (ORα) and ß (ORß) and clinicopathological features of the neoplasms. Twenty-six canine mammary tumour samples (11 benign, 15 malignant) were immunolabelled for AVPR2, ORα and ORß antigens. Moderate to intense immunolabelling of AVPR2 antigen, found in all neoplasms, was not significantly associated with expression of ORα or ORß antigens or with clinicopathological features. These findings indicate a potential role for AVPR2 in the development of canine mammary tumours and the use of AVPR2-selective vasopressin analogues as therapeutic options.

Expression of Oxytocin Receptors in Canine Mammary Tumours.

The aims of the present study were: (1) to investigate the presence of oxytocin receptors in benign and malignant canine mammary tumours (CMTs) and to evaluate the possible association between oxytocin receptor (OTR) expression and the expression of oestrogen receptor (OR) α and ORß, and (2) to examine associations between receptor expression and tumour size, clinical stage, histological subtype, tumour grading and lymph node status. Forty-three canine mammary tumour samples (19 benign, 24 malignant) were examined by immunohistochemistry to detect OTR, ORα and ORß expression. Results were expressed as total score for each receptor, calculated as the sum of the percentage of positive cells and the intensity of immunolabelling. In all of the evaluated mammary tumour samples, OTRs were identified and their expression tended to be higher in benign tumours than malignant tumours. Among the malignant tumours, the expression of OTR was significantly higher in grade I and II lesions than in grade III lesions. ORα-positive tumours had a tendency towards a higher OTR total score than ORα-negative tumours. These results report for the first time that CMTs express OTRs and their expression is associated with the presence of ORα. An interaction between oxytocin and the OTR might play a role in the development and progression of this type of neoplasia.

Synchronization of time of ovarian follicular development in llamas (Lama glama) using a protocol based on GnRH and PGF2α.

The aim of this study was to evaluate the effectiveness of a protocol based on GnRH and PGF2α to synchronize the emergence of a new wave of ovarian follicular development in llamas and, therefore, when a new dominant follicle develops. Llamas (n = 18) were assigned to growing, mature or regressing follicle groups according to the phase of the follicular wave at the beginning of treatment. The protocol was initiated with a GnRH analogue (GnRHa) injection on Day 0 followed 7 days later with a d-cloprostenol injection and a second GnRHa injection on Day 10. Ovulation rate after the first GnRHa treatment, day of new follicle emergence, mean plasma progesterone concentration and percentage of animals with a newly developed dominant follicle ≥ 7 mm on Day 10 were evaluated. Ovulation rate after the first GnRHa was less in the regressing than mature and growing follicle groups and new follicular wave emergence occurred earlier in the regressing follicle group than in the other two groups. Mean plasma progesterone concentration in females that had ovulations after the first GnRHa injection was similar. The percentage of animals that had a new follicle ≥ 7 mm on Day 10 was not different among groups and the overall percentage was 66.6%. The total synchronization rate for development of a new wave of follicular development on Day 10 was greater in females having ovulations after the first GnRHa injection than in those that did not have ovulations. In conclusion, the protocol used in the present study was useful for synchronizing ovarian follicular development in 66% of the llamas regardless of the phase of the follicular wave development at the beginning of treatment.

Hormonal changes and follicular activity after treatment with intravaginal progesterone-releasing devices in llamas.

Plasma progesterone (P4 ) concentrations and follicular activity after administration of different P4 doses were evaluated in 33 adult female llamas treated with intravaginal devices. In Study 1, a group of llamas (n = 10) was treated with an intravaginal device (IVD) containing 160 (n = 5) or 780 mg of P4 (n = 5). Based on the results from the first study, in Study 2, females with follicles at different stages of development were treated with the IVD containing 780 mg of P4 (n = 21) or remain untreated (control; n = 12) to evaluate the effect of P4 on follicular activity. In Study 1, the IVD containing 160 mg of P4 induced follicular turnover in 60% of females while the remaining 40% of llamas developed persistent follicles. Thus, this device controlled follicular activity in llamas, although it promotes the persistence of follicles present at start of treatment. Conversely, in both studies, the IVD containing 780 mg of P4 suppressed follicular development and hasten the emergence of a new follicular wave in all females regardless of the follicular phase at insertion. Additionally, in Study 2, this device effectively concentrated the appearance of follicles with ovulatory diameter at a definite time after treatment in comparison with control animals. In conclusion, treatment with an IVD containing 780 mg of P4 would be considered for the control of follicular activity in llamas as it ensures the presence of a young follicle with ovulatory diameter by day 6 after the end of treatment in all females.

Oestrogen and Progesterone Receptors and COX-2 Expression in Endometrial Biopsy Samples During Maternal Recognition of Pregnancy in Llamas (Lama glama).

Endometrial expression of oestrogen receptor-α (ERα), progesterone receptor (PR) and cyclooxigenase-2 (COX-2) was evaluated in non-pregnant and pregnant llamas during the period when luteolysis/maternal recognition of pregnancy is expected to occur. Females (n = 28) were divided into two groups: non-pregnant llamas were induced to ovulate with a Buserelin injection, and endometrial biopsies were obtained on day 8 (n = 5) or 12 (n = 5) post-induction of ovulation. Animals of the pregnant group (n = 18) were mated with a fertile male. Pregnancy was confirmed by the visualization of the embryo collected by transcervical flushing in 5 of 9 animals on day 8 post-mating and by progesterone profile on day 12 post-mating in 4 of 9 animals, when endometrial biopsies were obtained. An immunohistochemical technique was used to evaluate receptors population and COX-2 expression. Pregnant llamas showed a higher percentage of positive cells and stronger intensity for ERα than for non-pregnant llamas in stroma on day 8 and in the luminal epithelium on day 12 post-induction of ovulation, while a deep decrease in endometrial PR population was reported in pregnant llamas on that day in luminal and glandular epithelia and stroma. In the luminal epithelium, COX-2 expression was lower in pregnant than in non-pregnant animals. Briefly, the increase of ERα in pregnant llamas gives further support to the hypothesis that oestrogens are involved in the mechanism of maternal recognition of pregnancy. Endometrial PR decrease in pregnant llamas might be a necessary event to allow the expression of proteins involved in conceptus attachment, a mechanism widely accepted in other species. Moreover, embryo seems to attenuate maternal PGF(2α) secretion during early pregnancy by decreasing the endometrial expression of COX-2 in the luminal epithelium of pregnant llamas.

Ultrasonographic and endocrine characterization of follicular waves in llamas with a special reference to the overlapping phenomenon during successive waves.

Ovarian follicular growth in non-mated llamas occurs in successive waves that generally superimpose their origin on the regression of the preceding wave (overlapping), originating prolonged sexual receptivity in the species. The aim of this study was to perform an ultrasonographic and endocrine characterization of individual and successive waves in non-mated llamas with a special interest on the overlapping phenomenon. Twelve llamas were examined daily by transrectal ultrasonography for at least two consecutive waves. In six females, blood samples were collected daily at the end of each examination. The development of the largest follicle (F) showed a wavelike pattern with a mean duration of 25 days. All waves evaluated were partially overlapped on the preceding wave and emerged at a mean interval of 15.8 ± 0.5 days. This interwave interval determines a mean overlapping degree of 32% of the wave length. Similarly, mean plasma oestradiol-17ß (E2 ) concentrations followed a wavelike pattern. However, E2 concentrations started to decline before the structural regression of the F was observed. Mean basal E2 concentrations remain higher than 10.9 ± 0.6 pmol/l. In conclusion, follicular activity in non-mated llamas is characterized by continuous emergence of successive waves that always overlap the preceding wave with variable degrees. E2 production during the follicular wave is shorter in duration than the morphological development of the F. Finally, the overlapping phenomenon maintains increased plasma E2 concentrations persistently and this could explain the prolonged periods of sexual receptivity registered in llamas.

Oestrogen, progesterone and oxytocin receptors and COX-2 expression in endometrial biopsy samples from the induction of ovulation to luteolysis in llamas (Lama glama).

Endometrial expression of oestrogen (ERα), progesterone (PR) and oxytocin receptor (OR) and cyclooxygenase-2 (COX-2) was evaluated from the induction of ovulation to luteolysis in llamas. Ovarian activity was daily assessed by ultrasonography in five females. Ovulation was induced immediately after the detection of an ovulatory follicle by a GnRH injection (Day 0). Endometrial samples were obtained by transcervical biopsies from the left and right horns on day 0 and days 4, 8, 10 and 12 post-GnRH. Blood samples were collected daily for progesterone and estradiol-17ß determinations by RIA. An immunohistochemical technique was used to study receptors population and COX-2 expression which were then evaluated by two independent observers. The expression of ERα and PR was highest on day 0 in the luminal epithelium and stroma in association with high plasma estradiol-17ß concentrations. Thereafter, a decrease in ERα population was registered on day 4 and a new increase of its expression was observed between days 8 and 12 in those cell types. Conversely, PR population was gradually down-regulated until its lowest expression was reached on day 10 post-GnRH in the luminal epithelium. Content of OR was similar throughout the study in all cell types. The expression of COX-2 was highest from day 8 to 12 post-GnRH in the luminal epithelium, in relation to the time of maximal PGF2α release. Both steroid receptors populations and COX-2 expression were similar between horns. Meanwhile, OR expression was higher in the right than in the left uterine horn. In summary, this study showed that the loss of endometrium sensitivity to progesterone by days 8-10 post-induction of ovulation and the concomitant increase of COX-2 expression could play a key role in the mechanism of luteolysis and somehow be related to the short corpus luteum lifespan of llamas.

Development of corpus luteum susceptibility to an analog of prostaglandin F2α, throughout the luteal phase in llamas (Lama glama).

The aim of the present study was to evaluate the susceptibility of the corpus luteum to d-cloprostenol (synthetic analog of PGF(2α)) throughout the luteal phase in llamas. Female llamas (n=43) were induced to ovulate by GnRH injection in the presence of an ovulatory follicle and randomly assigned into one of six groups: control and treated with an injection of d-cloprostenol on Day 3, 4, 5, 6 or 8 post GnRH. Blood samples were collected to determine plasma progesterone concentrations. There was no effect of treatment on animals injected on Day 3 or 4 post-GnRH. In animals treated on Day 5, different responses were observed. No effect of treatment was recorded in 27% of the animals whereas 55% of the llamas showed a transitory decrease followed by a recovery in plasma progesterone concentrations after d-cloprostenol injection, indicative of a resurgence of the corpus luteum, extending the luteal phase a day more than in control animals. In the remaining 18% of the animals injected on Day 5, (corresponding to those exhibiting the greatest plasma progesterone concentrations at the day of injection), complete luteolysis was observed. Plasma progesterone concentrations decreased to below 1 ng ml(-1) 24 h after d-cloprostenol in llamas injected on Day 6 or 8 post-GnRH. In conclusion, the corpus luteum of llamas is completely refractory to PGF(2α) until Day 4 after induction of ovulation, being partially sensitive by Day 5 and fully responsive to PGF(2α), by Day 6 after induction of ovulation.

LH response of seasonally anovular Corriedale ewes acutely exposed to rams and estrous ewes.

Serial blood sampling before and after exposing four anovular Corriedale ewes to a group of rams and estrous ewes during the non-breeding season revealed a pattern of LH secretion similar to that previously observed in Merinos. Mean LH values doubled (P<0.001) from 0.24+/-0.06 microgL(-1) (mean+/-s.e.m.) before to 0.55+/-0.05 microgL(-1) after 2h of visual, auditory, and odor exposure to rams and estrous ewes in an indoor facility. A non-significant (P<0.17) increase of LH pulses per hour was also observed (0.7+/-0.3 pulses per hour before compared with 1.3+/-0.3 during stimulation). All four ewes had recently formed corpora lutea by five days after stimulation. Results are consistent with the pattern of sudden increase and sustained release of LH observed in other sheep breeds, particularly the Merino.

Uterine estrogen receptor alpha and progesterone receptor during the follicular and luteal phase in llamas.

Estrogen receptor-alpha (ERalpha) and progesterone receptor (PR) were characterized in different endometrial cell types as luminal and glandular epithelium and stroma during the follicular (FP) and the luteal phase (LP) in llamas. Animals were examined daily by transrectal ultrasonography for the determination of the presence of an ovulatory follicle and ovulation was immediately induced by a GnRH injection (Day 0). Endometrial samples were obtained by transcervical biopsies from the left uterine horn on Day 0 (FP) and 9 days after the GnRH injection (Day 9, LP). Blood samples were collected on these days for estradiol 17beta and progesterone determination by RIA. An immunohistochemical technique was used to visualize ERalpha and PR immunostaining which was then analyzed by two independent observers. Total positive area and average staining for ERalpha were affected by the phase of the ovarian activity: in the three cell types there was more positive area and intense staining during the FP than during the LP. Similar findings were observed for PR, more positive stained areas were found during the FP than during the LP in the epithelia. In addition, the three cell types had more intense staining during the FP than during the LP. An effect of the cell type for ERalpha and PR was observed; epithelia (luminal and glandular) had more positive stained areas and greater intensity than stromal cells. In conclusion, the results of the present study suggest that in llamas, like in other ruminants, estradiol has a stimulatory effect while progesterone downregulates the ERalpha and PR and that the receptor is cell type specific.

Effect of exogenous progesterone and eCG treatment on ovarian follicular dynamics in vicunas (Vicugna vicugna).

The aim of the present study was two-fold. First, to evaluate the effect of exogenous progesterone on ovarian follicular dynamics in order to assess its ability to synchronize ovarian activity in the vicuna. Secondly, to evaluate the ovarian response to the treatment with eCG through the observation of the structures developed in the ovaries. Follicular dynamics was monitored daily by transrectal ultrasonography in 12 adult, non-pregnant vicunas. Plasma progesterone and estradiol-17beta concentrations were measured in blood samples collected daily. In experiment 1, intravaginal devices containing 0.33g of progesterone were inserted into the vagina and kept in place for 5 days (treatment group, n = 8). After progesterone withdrawal, five animals were further monitored in order to evaluate the efficacy of the CIDR to synchronize the emergence of a dominant follicle. In experiment 2, four females received 750IU of eCG IM. Two were previously monitored ultrasonographically to confirm the absence of a dominant follicle at the beginning of the superstimulatory treatment (group A). The other two animals had a CIDR inserted into the vagina for 5 days and the superstimulatory treatment was applied 24h after device withdrawal (group B). Females from both groups were surgically explored 96 h after eCG injection; the ovaries were exposed and the number of newly formed structures produced by each ovary was counted. Peak progesterone concentrations (25.9 +/- 5.29 nmol l(-1), mean +/- S.E.M.) were attained on day 1 after device insertion, remained high until the day of device withdrawal (9.7 +/- 1.98 nmol l(-1)) and decreased to 5.5 +/- 1.13 nmol l(-1) the day after. There was no follicle development to the state of dominance after device insertion. Moreover, mean follicle diameter steadily decreased after insertion of the device until the minimum mean value (1.85 +/- 0.17 mm) was recorded on day 5 (P = 0.006). Similarly, plasma concentrations of estradiol-17beta remained below 35 pmol l(-1) during the period of progesterone treatment in all animals and the mean estradiol-17beta declined with the lowest value (22.1 +/- 2.19 pmol l(-1)) being recorded on day 4 after device insertion. After superstimulation of follicular development with eCG, the total number of follicles that developed was 33 in group A and 58 in group B and the mean number of newly developed ovarian structures per female was 22.75 +/- 4.26. In conclusion, progesterone released by the CIDR exerts a negative effect on ovarian follicular development and function suggesting intravaginal devices could be used to synchronize the beginning of follicular waves during a superstimulatory treatment. There was also a tendency for greater ovarian follicular development when the animals were previously treated with progesterone.

Follicular activity and hormonal secretory profile in vicuna (Vicugna vicugna).

The objective of the present study was to characterize ovarian activity in non-mated vicunas, relating ovarian structures (evaluated by transrectal ultrasonography, daily for 30 days) to changes in plasma concentrations of estradiol-17beta and progesterone. Ovarian follicular activity occurred in waves, characterized by the follicle emergence, growth and regression. The mean duration of follicular waves was 7.2+/-0.5 days (mean+/-S.E.M.), with a range of 4-11 days. The follicular growth phase averaged 3.0+/-0.2 days, the static phase 1.4+/-0.1, the regression phase 2.9+/-0.3 days, and the inter-wave interval was 4.2+/-0.3 days. The mean growth rate during the growing phase was 1.8+/-0.1mm/day, while the duration of the interval from 6mm to maximum diameter was 1.4+/-0.1 days. The mean maximum diameter of the dominant follicle was 8.4+/-0.3mm (range: 6.2-11.2) and mean diameter of the largest subordinate follicle was 5.4+/-0.1mm. There was an inverse relationship between the size of the largest follicle and the total number of follicles (r=-0.21, P=0.002). Follicle activity alternated between ovaries in 77% of the waves, with 40% of dominant follicles present in the left ovary and 60% in the right ovary. Plasma estradiol-17beta concentrations also had a wave-like pattern, varying between 12.0 and 62.8 pmol/l. Plasma progesterone concentrations remained below 5.0 nmol/l and there was no ultrasonographic evidence of ovulation during the study.

Levels of progesterone and changes in prostaglandin F(2alpha) release during luteolysis and early pregnancy in llamas and the effect of treatment with flunixin meglumine.

The secretory patterns of progesterone in relation to concentrations of 15-ketodihydro-PGF(2alpha) (PGFM) during the period of luteolysis or of maternal recognition of pregnancy were determined in the blood of llamas mated either with an intact or a vasectomized male. The ability of flunixin meglumine (FM) to postpone luteolysis in non-pregnant llamas was investigated by injecting the drug intravenously every 6 h at a dose of 2.2 mg/kg from days 6 to 12 post-copulation into a group of non-pregnant llamas. A pulsatile pattern of prostaglandin release was recorded during luteolysis in non-pregnant llamas, giving further support to the hypothesis that PGF(2alpha) is the luteolytic agent in llamas. The mean number of peaks per animal rose from 0.3 on day 7 to 3.8 on day 10 and then declined to 1.1 on day 12 with corresponding mean peak amplitude changing from 465 to 1234 and 566 pmol l(-1), respectively. In pregnant llamas, prostaglandin pulsatile release also occurred. The mean number of peaks per animal rose from 0.4 on day 7 to 0.8 on day 10 and then declined to 0.2 on day 11 and 0.6 on day 12, with corresponding mean peak amplitude changing from 494 to 676, 388 and 547 pmol l(-1), respectively. The transient decrease and subsequent recovery in progesterone concentrations was observed to occur in connection with prostaglandin release during early pregnancy. Oestradiol-17beta plasma peak concentrations attained after luteolysis were significantly higher than those recorded in early pregnant animals (around 30 pmol l(-1) and ll pmol l(-1)). Concentrations of PGFM decreased rapidly after the first administration of FM and remained low throughout the first 2 days of treatment. Thereafter, pulsatile release of prostaglandins started, and luteolysis proceeded; but a delay of 1-1.5 days in the progesterone decline was observed. Thus, it might be suggested that a higher dose and/or a more intensive injection schedule is required in llamas than in other ruminants to prevent luteolysis.

Plasma concentrations of 15-ketodihydro-PGF2 alpha, progesterone, oestrone sulphate, oestradiol-17 beta and cortisol during late gestation, parturition and the early post partum period in llamas and alpacas.

Plasma concentrations of 15-ketodihydroprostaglandin (PG) F2 alpha, progesterone, oestrone sulphate, oestradiol-17 beta and cortisol during late gestation, parturition and the early post-partum period were measured in six llamas and five alpacas. During the last 100 days of pregnancy, 15-ketodihydro-PGF2 alpha concentrations increased steadily until the day of parturition when a massive release was detected (P < 0.01) concomitant with a decrease in progesterone concentrations (P < 0.01). The highest PGF2 alpha metabolite concentrations (159 +/- 35 nmol l-1 and 92 +/- 29 nmol l-1 in llamas and alpacas respectively) were detected in the sample collected during the morning on the day of parturition. Basal concentrations were registered by day 3 after delivery. Plasma concentrations of oestrone sulphate started to increase 80 days before parturition and reached peak concentrations immediately before parturition (15 +/- 3 nmol l-1 in llamas and 18 +/- 5 nmol l-1 in alpacas). Oestrone sulphate concentrations dropped sharply (P < 0.01) on the day of parturition in llamas and one day later in alpacas, whereupon they remained relatively unchanged until at least 20 days postpartum. Oestradiol-17 beta concentrations were higher than 180 pmol l-1 during the last 45 days of pregnancy, began to decrease on the day of parturition and reached very low concentrations within the following two days. High oestradiol-17 beta concentrations were registered 7 days postpartum in all alpacas (P < 0.05) and within 10 days of parturition in five of six llamas (P < 0.01). No significant cortisol peaks were observed around parturition, but mean concentrations were increased in both species.

Endocrine changes during early pregnancy in the alpaca.

Plasma concentrations of progesterone, 15-keto-13, 14-dihydroprostaglandin F2 alpha and oestradiol-17 beta were monitored during early pregnancy in five alpacas. Heparinized blood samples were obtained every 15 min during a 4 h period (0800 to 1200 h) from day 8 to day 13 postmating. Mean plasma concentrations of oestradiol-17 beta decreased close to the detection limit of the assay from day 8 until days 10-11, whereupon they increased again until day 13. A rapid decline in progesterone concentrations occurred after day 8 postmating. All progesterone values registered after day 10 were significantly lower than those registered on day 8. After day 9 postmating, prostaglandin metabolite peaks were detected in all animals, indicating a temporal relationship between the progesterone decline and PGF2 alpha pulsatile release. The number of peaks detected during the 4-h period, monitored on each of the 5 days (day 9 to day 13), ranged from two to four in different animals. The analysis of the prostaglandin secretory pattern in pregnant alpacas suggests that PGF2 alpha peaks might occur at a frequency similar to that observed in nonpregnant animals but with a lower magnitude.

Endocrine changes after mating in pregnant and non-pregnant llamas and alpacas.

Plasma concentrations of oestradiol-17 beta, progesterone, 15-keto-dihydro-PGF2 alpha and luteinizing hormone (LH) were monitored in llamas and alpacas after mating with an intact male. Concentrations of LH and PGF2 alpha metabolite were high immediately after copulation. Ovulation occurred in 92% of the animals. The first significant increases in progesterone were recorded on day 4 after mating. In non-pregnant animals the lifespan of the corpus luteum was estimated to be 8-9 days. Luteolysis occurred in association with the release of PGF2 alpha. In pregnant animals, a transient decrease in progesterone concentrations was observed between days 8 and 18 in both species. No significant changes in PGF2 alpha secretion were registered during this period. Oestradiol-17 beta concentrations were high on the day of mating, declined to low values on day 4, and started to increase again on day 8. Peak values after luteolysis in non-pregnant animals were significantly higher than those registered in pregnant ones. Furthermore, concentrations of oestradiol-17 beta were elevated for a longer period in non-pregnant than in pregnant animals. The results suggest that progesterone from the corpus luteum exerts a negative influence on follicular activity in pregnant animals by reducing oestradiol-17 beta secretion.

Heterologous radioimmunoassay for llama and alpaca luteinizing hormone with a monoclonal antibody, an equine standard and a human tracer.

A radioimmunoassay for llama and alpaca LH was developed using a human I125LH tracer from a commercial kit, equine LH diluted in human LH free serum as standard, and a monoclonal antibody (518B7) specific for LH but with low species specificity. A 60-min delay in the addition of the tracer and overnight incubation gave a sensitivity of 0.8 microgram L-1. The intra-assay coefficient of variation was 37% at 1 microgram L-1, declined to 15% at 4 micrograms L-1 and was below 6% for concentrations up to 32 micrograms L-1. The inter-assay coefficients of variation for 3 control samples were 20% (2.8 micrograms L-1), 16% (7.1 micrograms L-1) and 9.8% (19 micrograms L-1). In an attempt to increase sensitivity, all tubes were preincubated for 4 h at room temperature before adding the tracer, and the sample volume was increased from 50 microL to 100 microL (in the standard curve the increased volume was compensated for by human LH free serum). With this protocol, the assay sensitivity was 0.5 microgram L-1. The assay was validated clinically and demonstrated increased concentrations of LH after mating in llamas and alpacas. Furthermore, the assay was used to monitor LH responses to a single dose of GnRH in llamas (adult males and females at different ages).

Physiological studies in the South American camelid llama (Lama guanicoe f. d. glama). I. Body water spaces and water turnover.

Body water (BW) and extracellular water (ECW), were determined with tritiated water (THO) and 82Br injected into the vein, to 8 mature animals of both sexes during the winter season. The biological half-time of THO (T1/2 THO) and the daily water turnover (WT) were measured and the intracellular water (ICW) calculated. The studies with THO were repeated in the same animals and in 2 lactating females in spring and summer. Two calves were also studied during spring. The values obtained in winter were: BW 659 +/- 12 ml/kg; T1/2 THO 9.2 +/- 1 day; WT per 24 h 50 +/- 3 ml/kg or 116 +/- 5 ml/kg 82 and 163 +/- 9 ml per 1 of BW82; ECW 215 +/- 8 ml/kg or 32.5 +/- 3% BW; ICW 447 +/- 12 ml/kg or 67.7 +/- 4% BW. The results of the spring's studies showed a significant increase in the values of WT. In summer a further increment of this parameters was observed when expressed as ml/kg body solids. This differences were remarkable in those in lactation. The proportion of water in the body was significantly higher during summer in all animals. BW in lactating animals during summer was 783 +/- 9 ml/kg and in the other animals 718 +/- 18; T1/2 THO values were 3.3 +/- .-06 and 4.5 +/- .4 day, respectively. WT was 396 +/- 9 ml/kg.82 or 484 +/- 8 ml/l BW82 in the lactating animals and 260 +/- 9 ml/kg 82 or 341 +/- 12 ml/l BW82 in the other animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Physiological studies in the South American camelid llama (Lama guanicoe f. d. glama). I. Body water spaces and water turnover

En ocho animales adultos de ambos sexos durante el invierno se determinaron mediante agua tritiada (THO) y 82Br. el agua corporal (AC) y extracelular (AEC) en forma simultánea. Se midieron el tiempo medio biológical del THO(T1/2THO) y el recambio diario de agua (RDA) y se calculó el agua intracelular (AIC). Los estudios con THO se repitieron en los mismos animales y en dos hembras en lactación durante la primavera y el verano. En la primavera también se estudaron dos animales lactantes. Los valores obtenidos en invierno fueron: AC 659 ñ 12ml/Kg; T1/2THO 9.2 ñ 1 día, RDA en 24h 50 ñ 3ml/Kg ó 116 ñ ml/Kg**.82 y 163 ml/AC**.82; AEC 215 ml/Kg ó 32.5 por ciento del AC. Los resultados registrados durante los estudios de primavera mostraron un incremento en los valores de RDA altamente significativo y en verano un aumento adicional en todos los animales, cuando los datos se expresan como porciento de los sólidos del cuerpo, ello fue más notable en las hembras en lactación. La porporción del AC fue también significativamente más alta en todos los animales en el verano. En los animales en lactación durante el verano el AC fue de 783 ñ 9ml/Kg y en los otros animales 718 ñ 18ml/Kg; los valores de T1/2 THO fueron 3.3 ñ 06 y 4.5 ñ 4 días, respectivamente. El RDA fue 396 ñ 9ml/Kg**.82 ó 484 ñ 8ml/l AC**.82 en los animales en lactación y 260ml/Kg**.82 ó 314 ñ 12ml/l AC**.82 en los otros animales. Los valores de RDA fueron más altos que los registrados en camellos dromedarios, pero más bajos que los reportados para diferentes tipos de bovinos, ovejas y cabras. Se postula que, aunque todos los camélos tienen un antecesor común y antecedentes evolutivos semejantes, las adaptaciones fisiológicas a condiciones desérticas diferentes, dio como resultado características particulares en el metabolismo del agua para cada especie

Physiological studies in the South American camelid llama (Lama guanicoe f. d. glama). I. Body water spaces and water turnover.

Body water (BW) and extracellular water (ECW), were determined with tritiated water (THO) and 82Br injected into the vein, to 8 mature animals of both sexes during the winter season. The biological half-time of THO (T1/2 THO) and the daily water turnover (WT) were measured and the intracellular water (ICW) calculated. The studies with THO were repeated in the same animals and in 2 lactating females in spring and summer. Two calves were also studied during spring. The values obtained in winter were: BW 659 +/- 12 ml/kg; T1/2 THO 9.2 +/- 1 day; WT per 24 h 50 +/- 3 ml/kg or 116 +/- 5 ml/kg 82 and 163 +/- 9 ml per 1 of BW82; ECW 215 +/- 8 ml/kg or 32.5 +/- 3

BW; ICW 447 +/- 12 ml/kg or 67.7 +/- 4

BW. The results of the springs studies showed a significant increase in the values of WT. In summer a further increment of this parameters was observed when expressed as ml/kg body solids. This differences were remarkable in those in lactation. The proportion of water in the body was significantly higher during summer in all animals. BW in lactating animals during summer was 783 +/- 9 ml/kg and in the other animals 718 +/- 18; T1/2 THO values were 3.3 +/- .-06 and 4.5 +/- .4 day, respectively. WT was 396 +/- 9 ml/kg.82 or 484 +/- 8 ml/l BW82 in the lactating animals and 260 +/- 9 ml/kg 82 or 341 +/- 12 ml/l BW82 in the other animals.(ABSTRACT TRUNCATED AT 250 WORDS)