Endothelial dysfunction in myometrial arteries of women with gestational diabetes

The Regulation of Endothelin-1 in Pregnancies Complicated by Gestational Diabetes: Uncovering the Vascular Effects of Insulin

Gestational diabetes mellitus (GDM) is a condition of pregnancy defined by new-onset hyperglycemia. GDM is associated with impaired maternal endothelial and vascular reactivity. Endothelin-1 (ET-1) is a potent vasoconstrictor that contributes to endothelial dysfunction, however, its abundance and actions in GDM are unclear. Maternal plasma was obtained from pregnancies complicated by GDM (n = 24) and gestation-matched controls (n = 42); circulating ET-1 levels were assessed by ELISA. Human omental arteries from healthy pregnancies and those complicated by GDM were dissected from omental fat biopsies and collected at cesarean section. mRNA expression of ET-1 and its receptors, ETA and ETB, in addition to vascular cell adhesion molecule-1 (VCAM1) and intercellular adhesion molecule-1 (ICAM1) were assessed by qPCR (n = 28). Using wire myography, we investigated vascular constriction to ET-1 (10-11-10-4 M) in omental arteries from pregnancies complicated by GDM, compared to gestation-matched controls (n = 7). GDM cases were stratified by clinical management, diet intervention (n = 5), or insulin treatment (n = 6). Additionally, arteries from healthy pregnancies were treated with insulin (1 mU/mL (n = 7) and 10 mU/mL (n = 5)) or vehicle control. Vasoactive response to ET-1 was measured via wire myography. Circulating ET-1 levels and mRNA expression of the ET-1 system in omental arteries were not found to be significantly different between pregnancies complicated by GDM compared to healthy controls. However, we found insulin treatment during pregnancy and in ex vivo models reduced ET-1 vasoconstriction of maternal vasculature in GDM. These data suggest insulin may improve vascular function in GDM, however, further investigation is needed to define the role of ET-1 in pregnancy.

Ca2+-Activated K+ Channels and the Regulation of the Uteroplacental Circulation

Adequate uteroplacental blood supply is essential for the development and growth of the placenta and fetus during pregnancy. Aberrant uteroplacental perfusion is associated with pregnancy complications such as preeclampsia, fetal growth restriction (FGR), and gestational diabetes. The regulation of uteroplacental blood flow is thus vital to the well-being of the mother and fetus. Ca²⁺-activated K⁺ (K_Ca) channels of small, intermediate, and large conductance participate in setting and regulating the resting membrane potential of vascular smooth muscle cells (VSMCs) and endothelial cells (ECs) and play a critical role in controlling vascular tone and blood pressure. K_Ca channels are important mediators of estrogen/pregnancy-induced adaptive changes in the uteroplacental circulation. Activation of the channels hyperpolarizes uteroplacental VSMCs/ECs, leading to attenuated vascular tone, blunted vasopressor responses, and increased uteroplacental blood flow. However, the regulation of uteroplacental vascular function by K_Ca channels is compromised in pregnancy complications. This review intends to provide a comprehensive overview of roles of K_Ca channels in the regulation of the uteroplacental circulation under physiological and pathophysiological conditions.

Potassium Channels in the Uterine Vasculature: Role in Healthy and Complicated Pregnancies

A progressive increase in maternal uterine and placental blood flow must occur during pregnancy to sustain the development of the fetus. Changes in maternal vasculature enable an increased uterine blood flow, placental nutrient and oxygen exchange, and subsequent fetal development. K⁺ channels are important modulators of vascular function, promoting vasodilation, inducing cell proliferation, and regulating cell signaling. Different types of K⁺ channels, such as Ca²⁺-activated, ATP-sensitive, and voltage-gated, have been implicated in the adaptation of maternal vasculature during pregnancy. Conversely, K⁺ channel dysfunction has been associated with vascular-related complications of pregnancy, including intrauterine growth restriction and pre-eclampsia. In this article, we provide an updated and comprehensive literature review that highlights the relevance of K⁺ channels as regulators of uterine vascular reactivity and their potential as therapeutic targets.

Endothelial Dysfunction in Pregnancy Complications

The endothelium, which constitutes the inner layer of blood vessels and lymphatic structures, plays an important role in various physiological functions. Alterations in structure, integrity and function of the endothelial layer during pregnancy have been associated with numerous gestational complications, including clinically significant disorders, such as preeclampsia, fetal growth restriction, and diabetes. While numerous experimental studies have focused on establishing the role of endothelial dysfunction in pathophysiology of these gestational complications, their mechanisms remain unknown. Numerous biomarkers of endothelial dysfunction have been proposed, together with the mechanisms by which they relate to individual gestational complications. However, more studies are required to determine clinically relevant markers specific to a gestational complication of interest, as currently most of them present a significant overlap. Although the independent diagnostic value of such markers remains to be insufficient for implementation in standard clinical practice at the moment, inclusion of certain markers in predictive multifactorial models can improve their prognostic value. The future of the research in this field lies in the fine tuning of the clinical markers to be used, as well as identifying possible therapeutic techniques to prevent or reverse endothelial damage.

Is FGF-23 an early indicator of atherosclerosis and cardiac dysfunction in patients with gestational diabetes?

OBJECTIVE

Fibroblast growth factor 23 (FGF-23) is a phosphorus-regulating hormone and plays a role in the pathogenesis of myocardial hypertrophy. The aim of this study was to evaluate the association of FGF-23 levels with echocardiographic parameters and insulin resistance (IR) in patients with gestational diabetes.

SUBJECTS AND METHODS

Fifty-four pregnant patients with gestational diabetes mellitus (GDM) (age, 31.12 ± 5.72 years) and 33 healthy pregnant women (age, 29.51 ± 4.92 years) were involved in the study. Fasting insulin, fasting plasma glucose (FPG), lipid profile, oral glucose tolerance test (OGTT), FGF23, echocardiographic parameters, and carotid artery intima-media thickness (CIMT) were evaluated in the two groups.

RESULTS

The two groups were not significantly different in age, sex, body mass index, lipid profile, or blood pressure. Insulin, homeostatic model assessment-insulin resistance (HOMA-IR), FGF-23 levels, CIMT, left ventricular (LV) mass, LV mass index and myocardial performance index (MPI) were significantly higher in the GDM group. HOMA-IR was positively correlated with FGF-23, and insulin was positively correlated with FGF-23. Additionally, FGF-23 was positively correlated with CIMT, LV mass index, and MPI.

CONCLUSION

Our findings suggest that monitoring serum FGF-23 may be useful as a non-invasive indicator of subclinical atherosclerosis in patients with GDM.

Impairment of IKCa channels contributes to uteroplacental endothelial dysfunction in rat diabetic pregnancy

Diabetes in rat pregnancy is associated with impaired vasodilation of the maternal uteroplacental vasculature. In the present study, we explored the role of endothelial cell (EC) Ca(2+)-activated K(+) channels of small conductance (SKCa channels) and intermediate conductance (IKCa channels) in diabetes-induced uterine vascular dysfunction. Diabetes was induced by injection of streptozotocin to second-day pregnant rats and confirmed by the development of maternal hyperglycemia. Control rats were injected with citrate buffer. Changes in smooth muscle cell intracellular Ca(2+) concentration, membrane potential, and vasodilation induced by SKCa/IKCa channel activators were studied in uteroplacental arteries of control and diabetic rats. The impact of diabetes on SKCa- and IKCa-mediated currents was explored in freshly dissociated ECs. NS309 evoked a potent vasodilation that was effectively inhibited by TRAM-34 but not by apamin. NS309-induced smooth muscle cell intracellular Ca(2+) concentration, membrane potential, and dilator responses were significantly diminished by diabetes; N-cyclohexyl-N-2-(3,5-dimethyl-pyrazol-1-yl)-6-methyl-4-pyrimidinamine (CyPPA)-evoked responses were not affected. Ca(2+)-activated ion currents in ECs were insensitive to paxilline, markedly inhibited by charybdotoxin (ChTX), and diminished by apamin. NS309-induced EC currents were generated mostly due to activation of ChTX-sensitive channels. Maternal diabetes resulted in a significant reduction in ChTX-sensitive currents with no effect on apamin-sensitive or CyPPA-induced currents. We concluded that IKCa channels play a prevalent role over SKCa channels in the generation of endothelial K(+) currents and vasodilation of uteroplacental arteries. Impaired function of IKCa channels importantly contributes to diabetes-induced uterine endothelial dysfunction. Therapeutic restoration of IKCa channel function may be a novel strategy for improvement of maternal uteroplacental blood flow in pregnancies complicated by diabetes.

Previous gestational diabetes history is associated with impaired coronary flow reserve

BACKGROUND

Gestational diabetes mellitus (GDM) is a prediabetic state that is known to increase the risk of cardiovascular diseases. We have investigated coronary flow velocity reserve (CFVR) and epicardial fat thickness (EFT), and left ventricular diastolic function in patients with a history of previous GDM (p-GDM).

METHODS

Ninety-three women with GDM history and 95 healthy women without GDM history were recruited. We used transthoracic Doppler echocardiography to assess CFVR, EFT, and left ventricular diastolic function. Insulin resistance of each subject was assessed with homeostasis model assessment insulin resistance (HOMA-IR). Hemoglobin A1c and high-sensitivity C-reactive protein (hsCRP) were also measured in all patients.

RESULTS

CFVR values were significantly lower (2.34 ± 0.39 versus 2.80 ± 0.24, p < 0.001) and EFT values were significantly higher in patients with p-GDM than the control group (5.5 ± 1.3 versus 4.3 ± 1.1, p < 0.001). E/E' ratio (7.21 ± 1.77 versus 6.53 ± 1.38, p = 0.003), hemoglobin A1c (5.2 ± 0.4 and 5.0 ± 0.3, p = 0.001), HOMA-IR (2.8 ± 1.4 versus 1.7 ± 0.9, p = 0.04), and hsCRP levels were significantly higher in the p-GDM group than the control group. Multivariate analysis revealed that gestational diabetes history is independently associated with CFVR.

CONCLUSION

Women with a GDM history may be at more risk regarding coronary microvascular dysfunction compared to the healthy ones.

Maternal serum glycosylated fibronectin as a point-of-care biomarker for assessment of preeclampsia

OBJECTIVE

We assessed the association of glycosylated fibronectin (GlyFn) with preeclampsia and its performance in a point-of-care (POC) test.

STUDY DESIGN

GlyFn, placental growth factor (PlGF), and soluble vascular endothelial growth factor receptor 1 (sFlt1) levels were determined in serum samples from 107 pregnant women. In all, 45 were normotensive and 62 were diagnosed with preeclampsia. The ability of GlyFn to assess preeclampsia status and relationships between GlyFn and maternal characteristics and pregnancy outcomes were analyzed.

RESULTS

GlyFn serum levels in the first trimester were significantly higher in women with preeclampsia (P < .01) and remained higher throughout pregnancy (P < .01). GlyFn, sFlt1, PlGF, and the sFlt1/PlGF ratio were significantly associated (P < .01) with preeclampsia status, and the classification performance of these analytes represented by area under the receiver operating characteristic curve was 0.99, 0.96, 0.94, and 0.98, respectively, with 95% confidence intervals of 0.98-1.00, 0.89-1.00, 0.86-1.00, and 0.94-1.00, respectively. Increased GlyFn levels were significantly associated with gestational age at delivery (P < .01), blood pressure (P = .04), and small-for-gestational-age neonates. Repeated-measures analysis of the difference in weekly GlyFn change in the third trimester demonstrated that mild preeclampsia was associated with a weekly change of 81.7 μg/mL (SE 94.1) vs 195.2 μg/mL (SE 88.2) for severe preeclampsia. The GlyFn POC demonstrated similar performance to a plate assay with an area under the receiver operating characteristic curve of 0.93 and 95% confidence interval of 0.85-1.00.

CONCLUSION

GlyFn is a robust biomarker for monitoring of preeclampsia in both a standard and POC format, which supports its utility in diverse settings.

Role of impaired endothelial cell Ca(2+) signaling in uteroplacental vascular dysfunction during diabetic rat pregnancy

Diabetes mellitus in pregnancy is associated with impaired endothelium-mediated dilatation of maternal arteries, although the underlying cellular mechanisms remain unknown. In this study, we hypothesized that diabetes during rat gestation attenuates agonist-induced uterine vasodilation through reduced endothelial cell (EC) Ca(2+) elevations and impaired smooth muscle cell (SMC) hyperpolarization and SMC intracellular Ca(2+) concentration ([Ca(2+)]i) responses. Diabetes was induced by an injection of streptozotocin to second-day pregnant rats and confirmed by the development of maternal hyperglycemia. Control rats were injected with a citrate buffer. Fura-2-based measurements of SMC [Ca(2+)]i or microelectrode recordings of SMC membrane potential were performed concurrently with dilator responses to ACh in uteroplacental arteries from control and diabetic pregnant rats. Basal levels of EC [Ca(2+)]i and ACh-induced EC [Ca(2+)]i elevations in pressurized vessels and small EC sheets were studied as well. Diabetes reduced ACh-induced vasodilation due to a markedly impaired EDHF-mediated response. Diminished vasodilation to ACh was associated with attenuated SMC hyperpolarization and [Ca(2+)]i responses. Basal levels of EC [Ca(2+)]i and ACh-induced EC [Ca(2+)]i elevations were significantly reduced by diabetes. In conclusion, these data demonstrate that reduced endothelium-mediated hyperpolarization contributes to attenuated uteroplacental vasodilation and SMC [Ca(2+)]i responses to ACh in diabetic pregnancy. Impaired endothelial Ca(2+) signaling is in part responsible for endothelial dysfunction in the uterine resistance vasculature of diabetic rats. Pharmacological improvement of EC Ca(2+) handling may provide an important strategy for the restoration of endothelial function and enhancement of maternal blood flow in human pregnancies complicated by diabetes.