scholarly journals Inhibition of the secretion of LH in ovariectomised pigs by sustained but not repeated acute elevation of cortisol in the absence but not the presence of oestradiol

1999 ◽  
Vol 163 (3) ◽  
pp. 477-486 ◽  
Author(s):  
AI Turner ◽  
PH Hemsworth ◽  
BJ Canny ◽  
AJ Tilbrook
Keyword(s):  
Acute Stress ◽  
Plasma Concentrations ◽  
Pulse Amplitude ◽  
Follicular Phase ◽  
Elevated Plasma ◽  
Acute Elevation ◽  
The Mean ◽  
The Impact ◽  
Lh Secretion ◽  
Prolonged Stress

Prolonged stress is known to impair reproduction. It has been proposed that reproduction will also be impaired when a severe acute stress occurs during a period of elevated plasma concentrations of oestradiol, such as during the follicular phase of the oestrous cycle. In this experiment, we hypothesised that repeated acute and sustained elevation of cortisol would suppress the secretion of LH in ovariectomised pigs and that these effects would be enhanced in the presence of oestradiol negative feedback. Cortisol (or vehicle) was administered 12 hourly to ovariectomised pigs (n=6/treatment) for 8 days in the absence of oestradiol treatment and for a further 8 days during treatment with oestradiol. Vehicle was administered to 'control' pigs, 10 or 20 mg cortisol was administered i.v. to pigs to produce 'repeated acute' elevation of cortisol and 250 mg cortisol was administered i.m. to pigs to give a 'sustained' elevation of cortisol. Both before and during treatment with oestradiol, plasma concentrations of LH were monitored on the day before treatment, on the 4th and 8th days of treatment and following an i.v. injection of GnRH at the end of the 8th day of treatment. The repeated acute elevation of cortisol did not impair any parameters of LH secretion (i.e. mean plasma concentrations of LH, pulse amplitude or frequency, pre-LH pulse nadir or the LH response to GnRH) in the absence or in the presence of oestradiol. In contrast, when the elevation of cortisol was sustained, the mean plasma concentrations of LH and the pre-LH pulse nadir were significantly (P<0.05) lower on the 8th day of treatment than on the day before treatment and on the 4th day of treatment. Nevertheless, no other parameters of LH secretion were affected and these effects only occurred in the absence (not in the presence) of oestradiol. In conclusion, cortisol needed to be elevated for more than 4 days to impair the secretion of LH, and oestradiol did not enhance the impact of cortisol on LH secretion in ovariectomised pigs.

Effects of acute stress on the patterns of LH secretion in the common marmoset (Callithrix jacchus)

1988 ◽  
Vol 118 (2) ◽  
pp. 259-264 ◽  
Author(s):  
K. T. O'Byrne ◽  
S. F. Lunn ◽  
A. F. Dixson
Keyword(s):  
Acute Stress ◽  
Mammalian Species ◽  
Physical Restraint ◽  
Plasma Concentrations ◽  
Social Rank ◽  
Pulse Amplitude ◽  
Common Marmoset ◽  
Pulse Frequency ◽  
Lh Releasing Hormone ◽  
Lh Secretion

ABSTRACT Stressful stimuli associated with aggressive encounters and low social rank may affect female fertility in a variety of mammalian species. In these experiments we examined the effects of aggressive encounters and physical restraint in a primate chair on the patterns of LH secretion in ovariectomized, oestrogen-primed female marmosets. Receipt of aggression from a female conspecific, followed by physical restraint for collection of blood samples (at 10-min intervals for 4 h), resulted in marked declines in LH concentrations during oestradiol-induced LH surges in five animals (from 112 ± 24 μg/l to 45±12 μg/l; group means ± s.e.m.; P<0·05). This was due to reductions in LH pulse amplitude rather than to changes in pulse frequency. Decreases in plasma concentrations of LH were reversed by treating females with exogenous LH-releasing hormone (LHRH). Cortisol treatment had no effect on LH levels during oestrogen-induced LH surges. Effects of aggressive encounters and physical restraint on plasma LH were not therefore due to reduced pituitary responsiveness to LHRH or to increased plasma concentrations of cortisol. In separate experiments it was found that physical restraint alone had no effect on plasma LH in habituated subjects, and that decreases in plasma LH after receipt of aggression only occurred if animals were subsequently placed in the restraint chair. A summation of stressful effects is therefore required to produce the fall in circulating LH. A summation of social and other environmental stressors may also underlie the reduced fertility seen in free-living animals. J. Endocr. (1988) 118, 259–264

Diurnal changes in the plasma concentrations of LH and hypothalamic contents of LHRH-I and LHRH-II in the domestic hen

1991 ◽  
Vol 130 (3) ◽  
pp. 457-462 ◽  
Author(s):  
S. C. Wilson ◽  
R. T. Gladwell ◽  
F. J. Cunningham
Keyword(s):  
Plasma Concentration ◽  
Diurnal Rhythm ◽  
Laying Hens ◽  
Plasma Concentrations ◽  
Posterior Hypothalamus ◽  
Anterior Hypothalamus ◽  
Diurnal Changes ◽  
The Mean ◽  
The Times ◽  
Lh Secretion

ABSTRACT Diurnal changes of LH secretion in sexually immature hens of 9, 11, 13 and 15 weeks of age consisted of 25–40% increases in the mean concentrations of LH in plasma between 15.00 and 18.00 h, i.e. between 2 h before and 1 h after the onset of darkness. During this time there was a tendency for the mean contents of LHRH-I in the anterior hypothalamus and posterior hypothalamus to increase by 21–74% and 20–56% respectively. In hens of 9 and 15 weeks, diurnal changes in the plasma concentration of LH closely paralleled those of LHRH-I content in the posterior hypothalamus. In contrast, the diurnal rhythm of LH secretion in hens of 11 and 13 weeks was more marked and plasma concentrations of LH continued to rise steeply between 18.00 and 21.00 h, i.e. between 1 and 4 h after the onset of darkness. At 11 weeks, this was associated with a reduction (P<0·01) in the contents of LHRH-I and LHRH-II, particularly in the anterior hypothalamus. In laying hens, a diurnal decline (P<0·01) in the plasma concentration of LH between 1 and 4 h after the onset of darkness was preceded by a fall (P<0·05) in the content of LHRH-I in the posterior hypothalamus and in the total hypothalamic content of LHRH-II (P<0·01). In all groups of hens, irrespective of the times of day at which tissue was taken, significant (P<0·05–<0·001) correlations between the contents of LHRH-I and LHRH-II in the anterior hypothalamus were observed. It is concluded that a diurnal rhythm of release of LHRH-I may drive the diurnal rhythm of LH secretion. Thus, in sexually immature hens of 9 and 15 weeks and laying hens in which diurnal changes in plasma LH were small there were parallel changes in the content of LHRH-I in the posterior hypothalamus. However, where the plasma concentration of LH was increased substantially, as at 11 weeks, there was a decline in the hypothalamic contents of LHRH-I. A simultaneous fall in the hypothalamic content of LHRH-II raises the possibility of a causal relationship between the activities of LHRH-II, LHRH-I and the release of LH. Journal of Endocrinology (1991) 130, 457–462

Plasma β-endorphin and LH during prolonged hypoglycaemia in ewes

1993 ◽  
Vol 1993 ◽  
pp. 93-93 ◽  
Author(s):  
A.M.X. Eloy ◽  
R.G. Rodway
Keyword(s):  
Plasma Concentrations ◽  
Reproductive Function ◽  
Opioid Peptide ◽  
Inhibitory Effect ◽  
Elevated Plasma ◽  
Lh Release ◽  
Lh Secretion

Normal reproductive function in female animals can be drastically impaired by a variety of stressful stimuli. For example, undernutrition and hypoglycaemia in sheep have been shown to suppress pulsatile LH secretion and to reduce the number of ewes showing pre-ovulatory LH peaks (Crump and Rodway 1986, Clarke et al. 1990). Similar stresses are also known to cause release of the opioid peptide β-endorphin into the circulation. Opioids are well-known to have a central inhibitory effect on LH release, although whether the elevated plasma concentrations of these peptides have any effect on LH secretion is unclear. The present study investigated the affect of insulin-induced hypoglycaemia on plasma concentrations of β-endorphin and LH.

Impact of pulsatility on the ensemble orderliness (approximate entropy) of neurohormone secretion

2001 ◽  
Vol 281 (6) ◽  
pp. R1975-R1985 ◽  
Author(s):  
J. D. Veldhuis ◽  
M. L. Johnson ◽  
O. L. Veldhuis ◽  
M. Straume ◽  
S. M. Pincus
Keyword(s):  
Half Life ◽  
Young Male ◽  
Approximate Entropy ◽  
Pulse Amplitude ◽  
Interval Length ◽  
Normal Female ◽  
Pulse Trains ◽  
Burst Amplitude ◽  
The Impact ◽  
Lh Secretion

Regular patterns of neurohormone secretion are driven by underlying pulsatile and subordinate (feedback sensitive) dynamics. Measures of time-series orderliness, e.g., the approximate entropy (ApEn) statistic (Pincus SM. Proc Natl Acad Sci 88: 2297–2301, 1991), vividly discriminate pathological and physiological patterns of hormone release. To investigate how specific pulsatility features impact regularity estimates, we have examined the sensitivity of the ApEn metric to systematic variations in the frequency, amplitude, and half-life of simulated neurohormone pulse trains (Veldhuis JD, Carlson ML, and Johnson ML. Proc Natl Acad Sci 84: 7686–7690, 1987) and compared the impact of a high vs. low baseline luteinizing hormone (LH) pattern regularity state mimicking the normal female luteal phase and the young male, respectively. Shortening the interpulse interval length elevated ApEn in both pulsatility models, thereby signifying greater ensemble series irregularity. The frequency sensitivity of ApEn was robust to several complementary renditions of ApEn and to variations in experimental uncertainty, basal (nonpulsatile) LH secretion, and secretory burst amplitude. ApEn rose with increasing hormone half-life, especially in the face of low baseline variability emulated by midluteal LH secretion profiles. High variability of secretory burst amplitude, pulse duration, or interpeak intervals increased ApEn in the more orderly femalelike construct; in the highly irregular malelike LH pulse model, these variability changes had little effect on ApEn. In summary, the ensemble regularity statistic, ApEn, quantifies unequal pattern orderliness in neurohormone pulse trains with minimal dependence on mean pulse amplitude, interpulse baseline, or (subthreshold) sample uncertainty. Thus ApEn monitors changing secretory event frequency and interpulse variability with sensitivity to starting pattern regularity, providing a mechanistic linkage between model evolution and statistical change.

P–663 The ratio of serum progesterone (P4) to the number of follicles (P4/Follicle) is a more objective parameter for euploidy rate as compared to systemic progesterone

2021 ◽  
Vol 36 (Supplement_1) ◽  
Author(s):  
K Ab. ali ◽  
B Lawrenz ◽  
A L Tegedor ◽  
F R Ruiz ◽  
A El-Damen ◽  
...  
Keyword(s):  
Oocyte Maturation ◽  
Ovarian Stimulation ◽  
Follicular Phase ◽  
Preimplantation Genetic Testing ◽  
Serum Progesterone ◽  
Final Oocyte Maturation ◽  
The Mean ◽  
A Prospective Study ◽  
The Impact ◽  
Ploidy Status

Abstract Study question Does the ratio of serum progesterone (P4) to the number of follicles (P4/Follicle) on the day of final oocyte maturation affect the ploidy status of the embryos? Summary answer A high P4/Follicle ratio negatively affects the euploid rate of the embryos. What is known already During ovarian stimulation, exogenous gonadotropins are administered to achieve multifollicular growth. Intense gonadotropin stimulation towards the end of the follicular phase seems to cause a premature progesterone rise in stimulated IVF cycles. The impact of serum progesterone elevation during the follicular phase has been studied intensively. Though most studies have focused on the effect of progesterone elevation on the endometrial receptivity, little is known about its possible impact on embryo development and ploidy status. The only study that investigated the effect of progesterone on the embryo ploidy status, was unable to show any significant impact. Study design, size, duration This retrospective study was performed at ART Fertility Clinics Abu Dhabi, UAE and Muscat, Oman. All stimulation cycles (n = 975) were performed between January 2015 to December 2019 with patients aged between 18–45, Body mass index (BMI) of 18–35, stimulated either with rFSH or hMG. All embryos underwent ICSI and Preimplantation Genetic Testing for Aneuploidies (PGT-A),Patients with surgical sperm extraction, warmed oocytes or natural cycle IVF were excluded. Participants/materials, setting, methods Serum P4 was measured on the last ultrasound prior triggering for final oocyte maturation. The P4/Follicle ratio was calculated as the ratio of P4 on trigger day to the number of follicles &gt; 10 mm on the last ultrasound. Serum P4 and P4/Follicle ratio were then analyzed using linear and univariate regression model to find potential correlation with the number of oocytes retrieved, number of mature oocytes, embryo quality (day 3 and 5), and euploid rate. Main results and the role of chance A total of 975 cycles were analyzed, with a mean age of 33.88±0.05 years, a mean BMI of 26.7±0.035 kg/m2. The mean number of oocytes collected was 12.53±0.058. Mean serum P4 on trigger day was 0.83±0.005 ng/ml and higher serum P4 values were observed as the number of oocytes retrieved and the number of mature oocytes increased (β = 0.026, p &lt; 0.0001 and β = 0.028, p &lt; 0.001, respectively). On the other hand, the mean P4/Follicle ratio was 0.056±0.00041 ng/ml and, unlike serum P4, the P4/Follicle ratio showed a negative correlation with the number of oocytes retrieved as well as with the number of mature oocytes (β=–0.001, p &lt; 0.001 and β=–0.001, p &lt; 0.001, respectively). While day 3 embryos were not affected by serum P4 or P4/Follicle ratio, the blastocyst quality was negatively affected by both increasing serum P4 levels and the P4/Follicle ratio (β=–0.012 p &lt; 0.05, β=–0.002, p &lt; 0.001, respectively). Euploid rates were positively correlated in cycles with increased serum P4 β = 0.18, p &lt; 0.001), while negatively correlated in cycles with a high P4/Follicle ratio (β=–0.015, p &lt; 0.001). After adjusting for potential confounders, only P4/Follicle remained as a significant negative factor for euploid rate (β=–0.004, p &lt; 0.001, 95% CI: –0.007- –0.001, p &lt; 0.001), which was not observed for serum P4 (p = 0.46). Limitations, reasons for caution This is an observational study based on retrospective data; an improved extrapolation of the results might be obtained by performing a prospective study. Wider implications of the findings: The findings of this study should encourage clinicians to optimize the ovarian stimulation protocols not only based on serum P4, but also considering the P4/Follicle ratio. Trial registration number Not applicable

Susceptibility of reproduction in female pigs to impairment by stress and the role of the hypothalamo - pituitary - adrenal axis

2002 ◽  
Vol 14 (6) ◽  
pp. 377 ◽  
Author(s):  
A. I. Turner ◽  
P. H. Hemsworth ◽  
A. J. Tilbrook
Keyword(s):  
Acute Stress ◽  
Adrenocorticotrophic Hormone ◽  
Short Term ◽  
Corticotrophin Releasing Factor ◽  
Other Substances ◽  
Reproductive Processes ◽  
The Impact ◽  
Prolonged Stress ◽  
Pituitary Adrenal Axis

Although it is generally considered that stress can impair reproduction, we suggest that the impact of acute or repeated acute stress or acute or repeated acute elevations of cortisol are of little consequence in female pigs, even if these occur during the series of endocrine events that induce oestrus and ovulation. It is important to understand the impact of acute stress on reproduction because, in the intensive production of livestock, animals are often subjected to short-term challenges. There seems little doubt that reproduction in a proportion of female pigs is susceptible to impairment by severe and prolonged stress or the sustained elevation of cortisol but only when this continues for a substantial period. In female pigs, where reproduction is susceptible to impairment by severe prolonged stress, it is possible that the mediators of this suppression are cortisol, corticotrophin-releasing factor and vasopressin but, in pigs, there is evidence to suggest that adrenocorticotrophic hormone is not involved. Other substances secreted during stress may be involved but these are not considered in this review. It is possible that the mediators of stress act at any level of the hypothalamo–pituitary–ovarian axis. Although a variety of experimental manipulations have provided potential mediators and mechanisms for the stress-induced suppression of reproduction, these experimental manipulations rarely represented physiological circumstances so it is not clear if such mechanisms would be important in a physiological context. The precise mediators and mechanisms by which hormones released during stress may inhibit reproductive processes during severe prolonged stress are yet to be determined.

Interpulse interval of GnRH stimulation independently modulates LH secretion

1989 ◽  
Vol 256 (4) ◽  
pp. E510-E515
Author(s):  
L. S. O'Dea ◽  
J. S. Finkelstein ◽  
D. A. Schoenfeld ◽  
J. P. Butler ◽  
W. F. Crowley
Keyword(s):  
Positive Relationship ◽  
Important Determinant ◽  
Pulse Amplitude ◽  
Gonadotropin Releasing Hormone ◽  
Interpulse Interval ◽  
The Mean ◽  
Normal Men ◽  
Low Amplitude ◽  
Lh Secretion ◽  
Independent Determinant

To examine the importance of the interpulse interval of gonadotropin-releasing hormone (GnRH) stimulation in modulating gonadotroph responsiveness, a fixed individualized dose of GnRH was administered to eight GnRH-deficient men at intervals selected randomly from the distribution of luteinizing hormone (LH) interpulse intervals of normal men. The responses were compared with data derived from a study of LH pulses in 20 normal men. A positive relationship was found between LH pulse amplitude and the preceding interpulse interval both in the GnRH-deficient (P less than 0.05) and in the normal (P less than 0.003) men. The distributions of LH pulse amplitudes appeared to differ between the two groups with failure of the study paradigm to reproduce the distribution of low-amplitude pulses of the normal men in the GnRH-deficient men. There was significantly more variability about the line that related interpulse interval and LH amplitude in the normal men (P less than 0.004) in whom the amount of GnRH could vary physiologically. This difference remained significant both for pulses with amplitudes below (P less than 0.01) or above (P less than 0.03) the mean of the normal men. These studies demonstrate that the GnRH interpulse interval is an independent determinant of pituitary responsiveness and that alterations in the amount of GnRH secreted from the hypothalamus are an important determinant of LH pulse amplitude in men.

scholarly journals Analysis of the impact of intravenous LH pulses versus continuous LH infusion on testosterone secretion during GnRH-receptor blockade

2012 ◽  
Vol 303 (10) ◽  
pp. R994-R1002 ◽  
Author(s):  
Johannes D. Veldhuis ◽  
Peter Y. Liu ◽  
Paul Y. Takahashi ◽  
Suanne M. Weist ◽  
Jean R. Wigham
Keyword(s):  
Rank Order ◽  
Approximate Entropy ◽  
Target Tissue ◽  
Deconvolution Analysis ◽  
Lh Pulsatility ◽  
Tissue Responses ◽  
Gonadotrophin Releasing Hormone ◽  
The Mean ◽  
The Impact ◽  
Lh Secretion

Gonadotrophin-releasing hormone (GnRH) pulsatility is required for optimal luteinizing hormone (LH) secretion, but whether LH pulsatility is required for physiological testosterone (T) secretion is not known. To test the postulate that pulses of recombinant human (rh) LH stimulate greater T secretion than continuous infusion of the same dose, a potent selective GnRH antagonist was administered overnight to 19 healthy men ages 18–49 yr. Subjects then received saline or rhLH intravenously continuously or as 6-min pulses intravenously every 1 or 2 h at the same total dose. Blood was sampled every 10 min for 10 h to quantify T responses. For the four interventions, the descending rank order of mean LH and mean T concentrations was 1-h = 2-h rhLH pulses > continuous rhLH > saline ( P < 10−3). Plateau LH and T concentrations correlated positively ( R2 = 0.943, P = 0.029) as did LH concentrations and LH half-lives ( R2 = 0.962, P = 0.019). Percentage pulsatile T secretion assessed by deconvolution analysis (Keenan DM, Takahashi PY, Liu PY, Roebuck PD, Nehra AX, Iranmanesh A, Veldhuis JD. Endocrinology 147: 2817–2828, 2006) was the highest ( P = 0.019), and half-time to attain peak T concentrations was the shortest ( P < 10−6), for 1-h rhLH pulses. Approximate entropy (a pattern-regularity measure) revealed more orderly T secretion for 1- than 2-h rhLH pulses ( P = 0.0076). Accordingly, a pulsatile LH signal, while not obligatory to maintain mean T concentrations, controls the mean plasma LH concentration and determines quantifiable patterns of T secretion. These data introduce the question whether blood T patterns in turn supervise distinctive target-tissue responses.

Mechanisms responsible for suppression of FSH and LH during lactation in the rat

1991 ◽  
Vol 129 (1) ◽  
pp. 119-130 ◽  
Author(s):  
K. Taya ◽  
S. Sasamoto
Keyword(s):  
Plasma Concentrations ◽  
The Other ◽  
Primary Role ◽  
Ovarian Steroids ◽  
Unilateral Ovariectomy ◽  
Peripheral Plasma ◽  
The Mean ◽  
Lh Secretion ◽  
Ovarian Inhibin ◽  
Venous Plasma

ABSTRACT Mechanisms responsible for suppression of FSH and LH secretion during lactation were investigated in rats, with special reference to the suckling stimulus and ovarian inhibin. Concentrations of immunoreactive inhibin in the peripheral plasma and bioactive inhibin in ovarian venous plasma were always low on days 3 and 5 of lactation in dams nursing eight pups, whereas values were always high on days 17 and 20 of lactation in dams nursing eight pups and on day 5 of lactation in dams nursing two pups. There was an FSH surge within 48 h after removal of litters on days 3 and 5 of lactation in dams nursing eight pups, whereas plasma concentrations of FSH were unchanged within 48 h by removal of litters on days 17 and 20 of lactation in dams nursing eight pups and on day 5 of lactation in dams nursing two pups. Plasma LH concentrations increased significantly compared with those of control animals within 24 h after removal of the litter on any day of lactation, regardless of the litter size. Plasma FSH levels increased within 6 h after bilateral or unilateral ovariectomy in lactating rats only on the days when plasma concentrations of inhibin were high before ovariectomy, such as day 17 of lactation in dams nursing eight pups and on day 5 of lactation in dams nursing two pups, whereas the mean concentrations of plasma LH showed no significant increase within 12 h after bilateral ovariectomy in these lactating rats. Treatment with progesterone or oestradiol-17β after unilateral ovariectomy did not inhibit the increase in plasma FSH levels, while the increase in plasma concentrations of FSH after surgery was completely inhibited by injecting inhibin (porcine follicular fluid). Treatment with steroid hormones inhibited the basal levels of LH in unilateral ovariectomized lactating rats. Plasma FSH concentrations increased sharply within 6 h after a single i.v. injection of anti-inhibin serum on days 10, 15 and 20 of lactation in dams nursing eight pups and on day 5 of lactation in dams nursing two pups, whereas only a small but significant increase in concentrations of FSH was noted 6 h after the antiserum treatment on day 5 of lactation in dams nursing eight pups. Concentrations of plasma LH were unchanged by treatment with antiserum in lactating rats throughout lactation. These findings indicate that the suckling stimulus, rather than ovarian factors, is mainly responsible for the suppression of FSH as well as LH secretion during the first half of lactation in rats nursing eight pups. On the other hand, during the second half of lactation in rats nursing eight pups and throughout lactation in rats nursing two pups, ovarian inhibin plays a primary role in the suppression of FSH secretion, whereas ovarian steroids act to suppress LH secretion. Journal of Endocrinology (1991) 129, 119–130

Erythrocyte cation fluxes during the menstrual cycle in normal female subjects

1987 ◽  
Vol 73 (2) ◽  
pp. 223-226 ◽  
Author(s):  
J. C. Monaghan ◽  
D. A. Willcocks ◽  
M. J. Sinosich ◽  
G. S. Stokes
Keyword(s):  
Menstrual Cycle ◽  
Plasma Concentrations ◽  
Follicular Phase ◽  
Renin Activity ◽  
Normal Female ◽  
Plasma Aldosterone Concentration ◽  
Rubidium Influx ◽  
The Mean ◽  
Female Subjects

1. Studies of erythrocyte cation transport mechanisms in vitro were performed on eight normotensive, premenopausal female subjects at the mid-points of the follicular and luteal phases of their menstrual cycles. Concurrent plasma concentrations of 17β-oestradiol, progesterone, aldosterone and renin activity were measured. 2. Ouabain-resistant, frusemide-resistant rubidium influx (an index of passive potassium diffusion) was significantly lower in the luteal than the follicular phase. 3. In further studies in four of the eight subjects, the mean rate constant of the rubidium influx measurement was also lower in the luteal than in the follicular phase. 4. There were no changes in Na+-K+ co-transport, sodium pump activity or intracellular cation concentrations throughout the cycle. 5. There was a tenfold fall in the mean plasma 17β-oestradiol/progesterone ratio, as well as increases in plasma aldosterone concentration and renin activity between the mid-follicular and mid-luteal phases. 6. We conclude that changes in plasma oestrogen/progesterone ratio during the menstrual cycle may be associated with alterations in passive potassium diffusion.

Sign in / Sign up

Export Citation Format

Share Document