The Journal of clinical endocrinology and metabolism
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J. Clin. Endocrinol. Metab. · Oct 1992
Contractile effects of prostaglandins, oxytocin, and endothelin-1 in human myometrium in vitro: refractoriness of myometrial tissue of pregnant women to prostaglandins E2 and F2 alpha.
Whereas there is much evidence in support of a role for prostaglandins (PG) in the parturitional process, it has not been demonstrated unequivocally that PGs are the physiological uterotonins involved in the induction of the myometrial contractions of spontaneous labor in women. This study was conducted to evaluate the contractile responsiveness of human myometrial tissue in vitro to PGs and to compare this response with that of other uterotonins, viz. oxytocin and endothelin-1. We found that treatment of uterine smooth muscle strips obtained from nonpregnant and pregnant women with PGE2 (10(-8)-10(-6) M) caused a biphasic response characterized by an initial single contraction of increased amplitude and duration, followed by relaxation and a long period (10-15 min) of quiescence. ⋯ Under identical in vitro conditions, PGF2 alpha (10(-8)-10(-6) M) and 15-methyl-PGF2 alpha (10(-6) M) caused sustained contractions in human vascular smooth muscle tissues (fetal aorta and arterial smooth muscle from chorionic vessels). Similarly, oxytocin and endothelin-1 (in myometrium from pregnant women) were effective in stimulating the force and frequency of myometrial contraction in vitro. We conclude that the myometrium of pregnant women, as evaluated in vitro, is refractory to the contractile effects of PGE2 and PGF2 alpha.
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J. Clin. Endocrinol. Metab. · Jul 1992
Diagnosis and therapy surveillance in Addison's disease: rapid adrenocorticotropin (ACTH) test and measurement of plasma ACTH, renin activity, and aldosterone.
The rapid ACTH injection test is an indirect screening test for adrenocortical insufficiency. As a supplement to this test, we evaluated the practicability of single measurements of plasma cortisol, ACTH, aldosterone, and PRA as a definitive diagnostic test of primary adrenocortical insufficiency (PAI). We also tested the value of PRA measurements during treatment with hydro- and fludrocortisone (HC and FC) as a guide for correct mineralocorticoid substitution. ⋯ PRA measurements during treatment with HC and FC correlated better with the mineralocorticoid dose than plasma potassium and sodium levels. PRA measurement is a valuable guide for FC replacement therapy. It should be titrated into the upper normal range to avoid under- and overtreatment.
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J. Clin. Endocrinol. Metab. · Jun 1992
Pyruvate dehydrogenase activity is stimulated by growth hormone (GH) in human mononuclear cells: a new tool to measure GH responsiveness in man.
Human peripheral mononuclear cells (PMC) were used to examine the effects of hGH and insulin on the activity of the pyruvate dehydrogenase (PDH) complex. Incubation of PMC with 10(-7) mol/L hGH or insulin increased basal PDH activity. Hormonal effects were maximal (50-60% above control values) at 15 min. ⋯ An increase of enzyme activity higher than 20% was observed in 26 patients out of 29 with hGH, and in 15 out of 18 with insulin. In conclusion, hGH is able to stimulate PDH activity of human mononuclear cells. This hormonal effect allows rapid evaluation of the cellular responsiveness of hGH in various pathophysiologic situations.
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J. Clin. Endocrinol. Metab. · Apr 1992
Free fatty acid metabolism in the follicular and luteal phases of the menstrual cycle.
To determine whether the hormonal changes associated with the normal menstrual cycle influence FFA metabolism, FFA turnover was measured in 12 women during both the follicular (days 4-10) and luteal (days 18-24) phases of their menstrual cycles. The luteal phase was confirmed by increased serum progesterone concentrations. ⋯ Finally, we compared the intraindividual variability of basal FFA flux from studies performed in different vs. the same phase of the menstrual cycle; no difference was present. We conclude that the cyclic changes in estrogen and progesterone production which occur during the normal menstrual cycle appear to have minor, if any, effects on FFA mobilization.
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J. Clin. Endocrinol. Metab. · Feb 1992
The role of cyclic adenosine 3',5'-monophosphate and polyol metabolism in diabetic neuropathy.
The effects of a stable prostacyclin analog, Iloprost, and aldose reductase inhibitors (ONO-2235 and isoliquiritigenin) were studied to elucidate the role of cAMP in diabetic neuropathy in relation to polyol metabolism. In in vivo experiments, the cAMP and myoinositol contents in sciatic nerves and motor nerve conduction velocity were significantly reduced in diabetic rats. Iloprost significantly restored the reduced cAMP content in sciatic nerves and improved motor nerve conduction velocity in diabetic rats. ⋯ In in vitro experiments, Iloprost significantly increased cAMP, but did not affect the sorbitol content in sciatic nerves. Aldose reductase inhibitors inhibited sorbitol accumulation and increased cAMP in sciatic nerves. Our data suggest that polyol pathway activation somehow results in cAMP reduction in sciatic nerves and that the reduction of cAMP in peripheral nerves may be closely related to the pathogenesis of diabetic neuropathy.