bluuebunny/crossref_metadata_2025 huggingface dataset:
Functional analysis of a novel pathogenic mutation affecting the gating glutamate of the 2Cl−/H+ exchanger ClC‐5 in patients with Dent's disease type 1
Authors: Bignon Yohan , Lahuna Olivier , Frachon Nadia , Teulon Jacques , Vargas‐Poussou Rosa , Lourdel Stéphane
Published: November 2023

Dent's disease is an X‐linked recessive renal tubular disorder characterized by low‐molecular‐weight proteinuria, hypercalciuria, nephrolithiasis, nephrocalcinosis, and progressive renal failure, inconstantly associated with other proximal tubular dysfunctions. Inactivating mutations of CLCN5, the gene encoding the 2Cl−/H+ exchanger ClC‐5, are associated with Dent's disease type 1. In the kidney, ClC‐5 is predominantly expressed at the apical membrane of proximal tubule cells and on early endosomes. Impaired endosomal acidification consecutive to ClC‐5 loss‐of‐function might explain the defective endocytosis in proximal tubule cells observed in patients with Dent's disease.

Here, we have investigated a novel ClC‐5 pathogenic missense mutation (E211G) affecting the gating glutamate that is responsible for coupling the Cl‐flux to the H+ counter‐transport in ClC 2Cl−/H+ exchangers. The courants were characterized using two‐electrode voltage‐clamp recordings in X. laevis oocytes. ClC‐5 subcellular localization was investigated in X. laevis oocytes using luminescence assays and in HEK293T cells using immunofluorescence. Protein expression was characterized in HEK293T cells using western‐blot.

The E211G mutant displayed a nearly linear current/voltage relationship. In contrast to those of wild‐type ClC‐5, currents of the mutant were not sensitive to extracellular acidification. We found no difference between this mutant and wild‐type ClC‐5 in terms of protein expression and subcellular targeting. The mutant trafficked normally to the cell surface and to the early endosomes and displayed complex glycosylation.

The present study demonstrates that the E211G mutation considerably affects electrical activity of ClC‐5 in proximal tubule cells.

Support or Funding Information

This work was supported in part by grant “Prix Jeune Chercheur” from “La Fondation du Rein”.
Functional and Brainstem Neurochemical Changes During a Critical Period of Postnatal Development
Authors: MacFarlane Peter , Mayer Catherine
Published: November 2023

There are distinct developmentally regulated changes in the constitutive expression of various neurochemical factors that occur in brainstem cardio‐respiratory control regions. Many of these neurodevelopmental events occur towards the end of the second postnatal (P) week of life in the rat and consist of abrupt and in some cases transient changes in the expression of various neurotransmitters (e.g. 5‐HT), glia (Iba‐1), cytokines (TNFα, IL1β), as well as components of the extracellular matrix (ECM). Such key events appear necessary for appropriate architectural organization of the maturing cardio‐respiratory nervous system, although their timing also coincides with a critical window during which the neonate exhibits a uniquely heightened and lethal vulnerability to “inflammatory” stressors. Specifically, exposure to five days of sustained hypoxia (SH, 11% O2) starting on day P11, or a single bolus injection of LPS (P12) cause profound disturbances in the acute hypoxic ventilatory response (HVR). The effects of SH and LPS appear unique to hypoxia as the hypercapnic ventilatory response is relatively less affected. LPS and SH are similar in that they each also cause an unexpected incidence of mortality which is unique to this age group as younger (P1–5) or older age groups (P21–25) appear relatively unaffected by exposure to the same stimuli, thus revealing a critical window of heightened cardio‐respiratory vulnerability. The heightened vulnerability to SH or LPS is associated with increased brainstem expression of microglia, the ECM, markers of neurogenesis and cytokines (mRNA), and a disruption to the serotonergic system. We propose, therefore, that the heightened vulnerability to either SH or LPS likely manifests as an aberrant “inflammatory” response during a critical period of brainstem neurochemical development and ECM formation, resulting in a lethal disturbance in crucial neurochemical/neurodevelopmental events. However, inhibition of microglia or enzymatic degradation of the ECM protects against the adverse effects of SH, whereas high serum TNFα represents an early biomarker that predicts vulnerability to LPS. These data have begun to shed light on the interactions between early life experiences and the cardio‐respiratory control system and the profound unintended consequences that they have during critical periods of development.
Phenotypic consequences of genetic deletion of the glial circadian clock Bmal1 in mice
Authors: Kofuji Paulo , Massman Logan , Engeland William
Published: November 2023

Glial cells have emerged as key players in brain information processing given the extensive neuronal‐glial and glial‐neuronal communication that takes place at synapses in the central nervous system. Glial cells also express an intrinsic molecular clock and release the neuromodulator ATP in a circadian fashion. Also disruption of glial signaling in fruit flies severely disrupts behavioral circadian rhythms. Collectively, these data suggest that glial cells and their intrinsic circadian rhythms have an important role in modulating circadian rhythmicity. In an effort to link glial cell‐specific circadian clocks to organismal circadian rhythmicity, we studied mice in which the canonical clock gene Aryl hydrocarbon receptor nuclear translocator‐like protein 1 (Bmal1) is selectively disrupted in astrocytes (GFAP‐Bmal1‐cKO). Staining of brain sections for BMAL1 reveals loss of expression in astrocytes, but not in neurons. By crossing GFAP‐Bmal1‐cKO mice with the Per2Luc knock‐in mice in which the clock gene Per2 is fused with the reporter gene Luciferase, we performed real time luminescence analysis of Per2 gene expression from cultured astrocytes and explant tissues. Cultured astrocytes from GFAP‐Bmal1‐cKO/ Per2Luc mice show reduced PER2Luc rhythmicity in comparison with control cultured astrocytes. Ex vivo explants from GFAP‐Bmal1‐cKO/Per2Luc mice of the suprachiasmatic nucleus, adrenal gland, cornea, lung, liver, and pituitary exhibited robust circadian rhythms of PER2Luc rhythmicity. Running wheel activity from GFAP‐Bmal1‐cKO mice subjected to a 12:12h light‐dark cycle reveals locomotor activity that was largely indistinguishable from wild‐type controls. In constant darkness, some mutant mice exhibited faster free running periods. Finally, some mutant mice also exhibited abnormal entrainment to a skeleton photoperiod. These experiments suggest an important role of the intrinsic circadian clock in glial cells for behavioral rhythmicity.

Support or Funding Information

RO3 NS3NS094419
Auto‐Immunity Targeting the Enteric Nervous System May Cause Constipation in Multiple Sclerosis
Authors: Spear Estelle T , Haag Melody M , Lavoie Brigitte , Applebee Angela , Teuscher Cory , Mawe Gary M
Published: November 2023

Multiple sclerosis (MS) is an inflammatory disease of the central nervous system (CNS) that is primarily associated with somatic motor, sensory, and visual deficits. This disease can also cause gastrointestinal (GI) dysmotility, including constipation, but the etiology of this symptom in MS is poorly understood. Additionally, patients with MS typically have serum antibodies against CNS myelin and neuronal proteins that are also found in the enteric nervous system (ENS). Here, we test the hypothesis that constipation in MS is caused by auto‐antibodies that target the ENS. First, we investigated whether serum from MS patients contains antibodies that are immunoreactive against ENS targets of guinea pig myenteric plexus. We found that MS serum (n=20) targets ENS cells more intensely than age and gender matched healthy serum (n=20) (p<0.05), with stained structures including enteric neurons and glia. Next, we tested whether mice with experimental autoimmune encephalomyelitis (EAE) exhibit signs of constipation by assessing whole GI transit, colonic propulsive motility, and fecal consistency. EAE was induced in C57BL/6 or SJL/J mice by immunization against mouse spinal cord homogenate. Whole GI transit was slower in EAE SJL mice than controls (p<0.05) but was not different in EAE C57 mice. Both SJL and C57 mice with EAE had significantly slower colonic transit than control mice of the same background (C57 & SJL p<0.05). The percentage of fecal water content was significantly lower in SJL and C57 EAE mice compared to controls (C57 p<0.01, SJL p<0.0001). To test whether antibodies play a role in GI dysmotility in EAE, we assessed motility in B cell deficient EAE mice (muMt− mice). Colonic transit time was slower in EAE muMt− mice compared to muMt− control mice (p<0.05), but there was no difference in fecal water content. In summary, these data demonstrate that serum antibodies in MS patients target the ENS and could cause constipation. Further, the EAE mouse model of MS has disrupted GI motility, and this effect is partially ameliorated in B cell deficient EAE mice. Together, these data suggest that GI dysmotility in MS involves an autoimmune mediated disruption of enteric neuro‐glial function.

Support or Funding Information

Supported by a pilot grant from the NMSS, and a predoctoral fellowship to ETS from NIDDK/NIH.
Nω‐Nitro‐L‐Arginine Methyl Ester (L‐NAME) induced hypertension and cardiorenal oxidative stress: Modulatory effect of the methanolic extract of Azadirachta indica
Authors: Omobowale Temidayo Olutayo , Oyagbemi Ademola , Ugbor Fisayo , Adejumobi Olumuyiwa , Adedapo Adeolu , Yakubu Momoh
Published: November 2023

Hypertension, a sustained elevation of blood pressure is known to cause both structural and functional abnormalities in both the cardiovascular and renal systems. In this study, we investigated the modulatory effects of the methanol extract of the leaves of Azadirachta indica (AI) on L‐NAME‐induced hypertension and cardiorenal dysfunction via oxidative stress in rats.

Fifty rats divided into five (5) groups each containing 10 animals were used in this study. Group A (Control) received only clean tap water for twenty‐one (21) days. Group B was treated orally with L‐NAME alone at the dosage of 40 mg/kg for 21 days. Groups C and D were treated orally with the methanol extract of AI at 100 mg/kg and 200 mg/kg, respectively together with L‐Name for 21 days, while Group E received Enalapril at the dosage of 25 mg/kg alongside L‐NAME for 21 days. Systolic, diastolic and mean arterial pressures were recorded in conscious animals before the termination of the experiment by tail cuff plethysmography. The animals were thereafter fasted overnight, sacrificed and the hearts and kidneys were removed from the animals in each group. Biochemical assays to assess the antioxidant defence system and oxidative stress markers were carried out on cardiac and renal tissues.

Treatment with L‐NAME led to a significant (p <0.05) increase in blood pressure and markers of oxidative stress in cardiac and renal tissues. AI caused an improvement in antioxidant defence systems, reduction in markers of oxidative stress and the restoration of blood pressure comparable with that of Enalapril.

This study suggests that the methanol extract of AI possesses modulatory functions in L‐NAME induced hypertension and cardiorenal oxidative stress.

Support or Funding Information

None
6β‐Hydroxytestosterone, a Cytochrome P450 1B1 Metabolite of Testosterone, Contributes to Angiotensin II‐Induced Vascular Dysfunction in Male Mice
Authors: Pingili Ajeeth K , Jennings Brett L , Malik Kafait U
Published: November 2023

Previously, we showed that 6β‐hydroxytestosterone (6β‐OHT), a cytochrome P450 1B1 (CYP1B1)‐derived metabolite of testosterone, contributes to the development of angiotensin II (Ang II)‐induced hypertension and renal dysfunction in male mice. Ang II‐induced hypertension is associated with vascular dysfunction. In the present study we determined the contribution of 6β‐OHT to Ang II action on vascular reactivity, endothelial dysfunction, hypertrophy and fibrosis. In Ang II‐treated Cyp1b1+/+ mice, responses of the thoracic aorta to phenylephrine (PE) and endothelin‐1 (ET‐1), media to lumen ratio were significantly increased compared to Ang II‐treated Cyp1b1−/− or castrated Cyp1b1+/+ mice. Treatment of the later two groups of mice with 6β‐OHT restored the effect of Ang II to increase responses of the thoracic aorta to phenylephrine (PE) and endothelin‐1 (ET‐1) and media to lumen ratio. Ang II infusion caused endothelial dysfunction, as indicated by decreased relaxation to acetylcholine (ACh) of the aorta from Cyp1b1+/+ but not Cyp1b1−/− or castrated Cyp1b1+/+ mice. 6β‐OHT did not alter Ang II‐induced endothelial dysfunction in Cyp1b1+/+ mice but resulted in endothelial dysfunction in Cyp1b1−/− or castrated Cyp1b1+/+ mice. Sodium nitroprusside(SNP)‐induced relaxation of the aorta was not altered in all the groups. Ang II infusion increased vascular fibrosis as indicated by increased α‐smooth muscle actin and collagen deposition, and reactive oxygen species production (ROS) as indicated by increased dihydroethidium (DHE) staining in Cyp1b1+/+ as compared to Cyp1b1−/− or castrated Cyp1b1+/+ mice. 6β‐OHT did not alter Ang II‐induced fibrosis or oxidative stress in Cyp1b1+/+ mice, however in Cyp1b1−/− or castrated mice it restored these effects of Ang II. These data suggest that 6β‐OHT contributes to the development of hypertension, most likely via increased ROS generation and vascular reactivity and hypertrophy, and that CYP1B1 could serve as a novel target for the development of agents that mitigate hypertension and associated pathogenesis.

Support or Funding Information

This work was supported by the National Institutes of Health and National Heart, Lung, and Blood Institute grants R01HL‐19134–40 and R01HL‐079109‐09
Hypertensive Pregnancy and the Relationship between Bone Mineral Density and Coronary Artery Calcification in Postmenopausal Women
Authors: Beckman John P , Camp Jon J , Lahr Brian D , Kearns Ann E , Miller Virginia M , Holmes David R
Published: November 2023

Objective

Preeclampsia, a hypertensive pregnancy disorder, increases the risk for cardiovascular disease including coronary artery calcification (CAC) as women age. Controversy exists regarding the relationship between bone mineral density (BMD) and CAC in menopausal women. This study was designed to determine and compare the relationship between BMD and CAC in postmenopausal women with defined histories of either normotensive or preeclamptic pregnancies.

Methods

Women who gave birth in Olmsted County, MN between 1976 and 1982 were identified from their medical record as having a preeclamptic pregnancy (PE, n=40) and were age/parity‐matched with women having normotensive pregnancies (NP, n=40). The study was approved by the IRB at Mayo Clinic and all participants gave written informed consent. Quantitative Computed Tomography was used to assess vertebral (T7‐9) BMD and CAC. Statistical analyses included linear regression with general estimating equation (GEE) to correct for within‐subject correlations.

Results

Women averaged 35 years since the index pregnancy and were 60 years of age at the time of the study. CAC was significantly greater in women of the PE group (median (25th, 75th percentiles: 0 (0, 0.3) NP and 0 (0, 25) PE, P=0.026). There were no significant differences in cortical, trabecular or central BMD between PE and NP groups. However, there was a positive correlation between cortical BMD and CAC in the PE group (ρ=0.336, P=0.042) and a negative correlation between central BMD and CAC in the NP group (ρ=−0.392, P=0.017).

Conclusions

Although CAC was greater in women with a history PE, BMD did not differ from women with a history of NP. Associations between cortical and central BMD with CAC differed by pregnancy history suggesting that there may be underlying differences in calcium metabolism associated with PE.

Support or Funding Information

This work was funded by grants from the NIH AG44170, AG034676, UL1 TR000135 and the Mayo Foundation.
The cardiovascular response to stroke in normal and hypertensive rats ‐ therapeutic or pathological?
Authors: McBryde Fiona , Thakkar Pratik , McGregor Ailsa , Paton Julian , Barrett Carolyn
Published: November 2023

Over 80% of ischemic stroke patients show an abrupt increase in blood pressure (BP) in the hours and days following stroke; yet whether post‐stroke hypertension is beneficial or harmful remains controversial, and the underlying physiological basis is unclear. We propose that one reason for this uncertainty may be a difference in the cardiovascular response to stroke between normotensive subjects compared to those with pre‐existing hypertension. We hypothesized that hypertensive subjects may be less able to increase blood pressure after stroke.

To investigate the dynamic cardiovascular response to stroke, Wistar (n=6, 393±34g) and spontaneously hypertensive (SH) rats (n=6, 377±29g) were placed under isofluorane anaesthesia (~3%), and instrumented with radio telemeters to record BP, ICP and brain tissue oxygen (p02) in the region of the future stroke penumbra. After a 1‐week recovery period, an ischemic stroke was induced via transient middle cerebral artery occlusion on Day 0, and recordings continued for 10 days after stroke.

In both Wistar and SH rats, penumbra p02 decreased to less than half baseline levels during the 2‐hour occlusion period, but rapidly recovered to baseline levels within minutes of reperfusion. In Wistar rats, BP increased rapidly (+37±4 mmHg above baseline of 108±6 mmHg; p<0.01) within 48 hours of stroke, before returning to baseline levels by Day 4. The magnitude of the post‐stroke blood pressure increase was similar in SH rats, (+34±3 mmHg above a hypertensive baseline of 145±5 mmHg; p<0.01), however SH rats showed a more gradual return to baseline levels by Day 7 (p=0.0459). ICP reflects cerebral oedema, and was also increased after stroke in both groups, peaking at 16±5 mmHg (p=0.035) on Day 3 in Wistars, with a slightly but significantly smaller increase of 7±1 mmHg (p<0.01) in SH rats. Following re‐perfusion, penumbra p02 tended to remain at or above baseline levels for the full recording period in both rat groups.

Contrary to our hypothesis, we found that ischemic stroke was associated with very similar patterns of elevated blood pressure and intracranial pressure, and steadily maintained penumbra tissue oxygen content, in both normotensive and hypertensive rats. That this post‐stroke surge in blood pressure persists even in subjects with pre‐existing hypertension, suggests that it may play a fundamental role in the defensive response to stroke. Future studies will determine the impact of preventing post‐stroke hypertension on the recovery from stroke, in particular the ability to maintain penumbra p02.

Support or Funding Information

Supported by the Health Research Council of New Zealand, the EU IRSES scheme and Royal Society Newton Fellowship Alumni funding.
Interaction between angiotensin II (ANGII) receptor 1A (AT1AR) and adenosine receptors in the control of vascular function in mouse aorta and mesenteric arteries
Authors: Yadav Vishal R , Teng Bunyen , Mustafa Jamal S
Published: November 2023

ANG II, a systemic vasoconstrictor and adenosine through its receptors (ARs) regulate vascular function. Recently, we have shown that acute ANG II stimulation enhanced A1AR dependent CYP4A mediated contraction in mesenteric arteries (MA). In addition, A2BAR dependent and partly KATP channel mediated relaxation was also reduced in MAs after ANG II stimulation (Yadav et al., 2015). Thus, suggesting a possible interaction between ARs and AT1R in the control of vascular function. The present study is designed to explore interaction between AR and AT1R. There are two types of AT1 receptors; AT1A is ubiquitously expressed where as AT1B expressed in aorta, resistance arteries, adrenal glands, pituitary, and hypothalamus. Considering ubiquitous tissue expression of AT1A receptors, we performed muscle tension studies in isolated MA and aorta from WT and AT1A KO mice. We used DMT wire myograph for MAs and organ bath for aortas to perform concentration response curves (CRCs) to various agonists. Our data showed a significant increase in contraction to A1AR agonist CCPA in MAs isolated from AT1A KO. The contraction observed at 10 and 100 nM of CCPA was 24.8 ± 13.7 (% PE) and 29.7 ± 14.8 in AT1A KO mice which was significantly higher compared to −4.8 ± 3.7 and 0.5 ± 3.2 observed in WT mice. NECA (non‐selective AR agonist) induced CRC was similar in WT and AT1A KO MAs. Pinacidil (KATP channel opener) and C21 (AT2 agonist) produced comparable CRCs in WT and AT1A KO MAs. In addition, comparable ACh, PE and KCl‐induced responses were present in MAs. In aorta, CRCs to CCPA, NECA, C21 and Pinacidil were comparable between WT and AT1A KO. However, PE‐induced contraction was significantly reduced in aorta of AT1A KO mice. ACh induced relaxation in aorta was 54.1 ± 4.4 (% PE) in AT1A KO compared to WT, 40.7±4.6 (p<0.05). Comparable contraction to ANG II in MAs suggests the involvement of AT1B receptors which needs further investigation. In conclusion, our data suggest an interaction between ARs and AT1A receptor in the control of vascular function.

Support or Funding Information

Supported by HL 027339
Beneficial renal effect of multi‐glycoside of Tripterygium wilfordii Hook. F. in mice with salt‐sensitive hypertension
Authors: Wang Youping , Zhu Minjun , Wang Zhentao , Cui Lin , Liu Suxiao , Xie Shiyan , Shen Si , Xu Hui
Published: November 2023

To clarify the effects of low‐dose of multi‐glycoside of Tripterygium wilfordii Hook. F. (GTW), an extract from a Chinese herb thunder god vine, on salt‐sensitive hypertension‐induced renal damage, we induced hypertension by uninephrectomy and deoxycorticosterone (DOCA)‐salt in mice with or without low‐dose of GTW treatment. DOCA‐salt treatment for 5 weeks increased mean arterial pressure (MAP) (P<0.01) and urinary albumin excretion (P<0.05), and also induced renal hypertrophy (P<0.01) compared with the control. Periodic acid‐Schiff and Masson's trichrome staining showed that DOCA‐salt treatment caused obvious glomerulosclrosis and tubulointerstitial injury in the renal cortex (P<0.05), and tubulointerstitial fibrosis compared with the control mice. Consistent with the results, renal collagen level determined using hydroxyproline assay was higher in DOCA‐salt‐treated mice compared with the control mice (P<0.05). Treatment with GTW at the low dose of 11.5 mg/kg/day by gavage had no effect on MAP and renal hypertrophy. However, it partially prevented renal morphological damage and reduced the increases in urinary albumin excretion and renal collagen (P<0.05). Our data showed that treatment with the low dose of GTW prevented renal damage induced by DOCA‐salt hypertension independently of their effects on blood pressure. The results indicate that low‐dose of GTW exhibits a protective effect on renal damage during salt‐sensitive hypertension. This work was supported in part by the National Natural Science Foundation of China (No. 81673734) and Henan Provincial Science and Technique Foundation for International Cooperation Program (No. 162102410048)

Support or Funding Information

This work was supported in part by the National Natural Science Foundation of China (No. 81673734) and Henan Provincial Science and Technique Foundation for International Cooperation Program (No. 162102410048)
Hypertension reduces expression of soluble guanylyl cyclase in the aorta via the Notch signaling pathway
Authors: Rippe Catarina , Zhu Baoyi , Krawczyk Katarzyna , Van Bavel Van Bavel Ed , Albinsson Sebastian , Sjölund Jonas , Bakker Erik N.T.P. , Swärd Karl
Published: November 2023

Hypertension is a dominating risk factor for cardiovascular morbidity and mortality. Here, aiming to characterize the genomic response of the vascular wall to hypertension, we administered physiological saline (NaCl, n=6) or angiotensin II (AngII, n=6) to mice using osmotic mini‐pumps and performed gene expression analysis using microarrays. AngII treatment (3w) resulted in a robust increase in blood pressure (186±6 vs. 103±11 mmHg) and altered expression (at q=0) of 235 genes in the aorta, including GUCY1A3 and GUCY1B3 which encode subunits of soluble guanylyl cyclase (sGC), the major nitric oxide receptor in the vascular wall. Quantitative RT‐PCR, western blotting and immunohistochemistry confirmed repression of sGC, and myograph experiments disclosed curtailed relaxation in response to the sGC activator BAY 41‐2272. To decipher underlying mechanisms we analyzed abundance of transcription factor binding motifs in promoters of differentially expressed genes, and identified enrichment (P=0.01) of RBPJ sites. RBPJ (recombination signal binding protein for immunoglobulin kappa J region or CBF1) is a core component of the NOTCH signaling pathway, and we accordingly found that the NOTCH caoctivators FRYL (FRY like transcriptional coactivator) and MAML2 (mastermind like transcriptional coactivator 2) were reduced in hypertension. Gain and loss of function experiments in smooth muscle from mice and humans demonstrated that JAG/NOTCH signaling controls sGC expression together with the coactivators MAML2 and FRYL. We also found altered expression of sGC, correlating with differential expression of MAML2, in stroke prone and spontaneously hypertensive rats. Finally, using RNA‐Seq data from the human coronary artery, we found compelling correlations between JAG1, NOTCH3, MAML2 and FRYL and the sGC subunits GUCY1A3 and GUCY1B3. Taken together, these studies suggest that NOTCH signaling provides a constitutive drive on expression of the major nitric oxide receptor (GUCY1A3/GUCY1B3) in systemic arteries from mice and humans, and that this homeostatic control mechanism is disturbed in hypertension.

Support or Funding Information

This study was supported by The Swedish Research Council K2015‐65X‐22662‐01‐03, The Crafoord Foundation and SMARTER a Marie Curie Initial Training Network.
Glucocorticoid Sensitivity and Systolic Blood Pressure During Graded Submaximal Exercise
Authors: Del Corral Pedro , Mancol Faith Laureen V , DePasquale John , Haug Andrew , Teelucksingh Surujpal
Published: November 2023

Background

The exaggerated systolic blood pressure (SBP) response to exercise predicts future hypertension and coronary artery disease. Hypertension has been associated to an increase in glucocorticoid sensitivity. Little is known about the effects of glucocorticoid sensitivity on the exaggerated SBP response to submaximal exercise.

PURPOSE

The aim of this study was to examine the relationship between glucocorticoid sensitivity and the systolic blood pressure response to graded submaximal exercise (GSE) on a cycle ergometer.

METHODS

Twenty two (19M, 3F) non‐hypertensive subjects (111.3/64.3 mmHg ± 1.9/1.4) underwent the dermal vasoconstrictor assay, using beclomethasone dipropionate, to determine glucocorticoid sensitivity, and subjects completed the GSE test with serial SBP measurements. Pearson's correlations were used to examine the relationship between glucocorticoid sensitivity and peak‐SBP. Subjects were dichotomized for glucocorticoid sensitivity, the upper and lower tertiles (11.4 ± 0.8 vs 3.2 ± 0.8, respectively; p<0.05) were compared for peak SBP during GSE and for rest to peak‐BP (Δ‐SBP).

RESULTS

There was a moderate association between dermal glucocorticoid sensitivity and peak SBP (r = 0.550, p<0.05), and Δ‐SBP (r = 0.497, p<0.05). Subjects on the upper tertile for glucocorticoid sensitivity had significantly higher peak SBP (189.2 ± 5.6 mmHg vs 155.5 ± 5.2 mmHg, p<0.05) and Δ‐SBP (76.9 ± 5.9 mmHg vs 48.2 ± 5.0 mmHg, p<0.05), compared to subjects on the lower tertile.

CONCLUSIONS

These findings suggest that individuals with a high glucocorticoid sensitivity, as suggested by the dermal vasoconstrictor assay SCORE, have a greater submaximal exercise peak SBP and Δ‐SBP, compared to those with a low glucocorticoid sensitivity.

Support or Funding Information

Benedictine University Summer Research Program
Arterial smooth muscle cell PKD2 (TRPP1) channels control systemic blood pressure
Authors: Bulley Simon , Leo M. Dennis , Hasan Raquibul , Fernandez‐Pena Carlos , Evanson Kirk W. , Burris Sarah K. , Wang Qian , Kuruvilla Korah P. , Jaggar Jonathan H.
Published: November 2023

Autosomal dominant polycystic kidney disease (ADPKD), an inherited condition that affects approximately 1 in 800 people, occurs due to mutations in either PKD1 or PKD2 proteins. Although ADPKD is characterized by the formation of kidney cysts, patients suffer from cardiovascular diseases, including hypertension, often with no alteration in renal function. PKD2 is a six transmembrane domain transient receptor potential (TRP) channel that is also termed TRPP1. Recent evidence suggests that PKD2 is expressed in arterial smooth muscle cells, but functional significance is poorly understood. Similarly unclear is the regulation of blood pressure by arterial smooth muscle cell TRP channels. Here, we generated a novel, conditional smooth muscle‐specific PKD2 knockout (PKD2sm−/−) mouse model to investigate the regulation of systemic artery contractility and blood pressure by PKD2. PKD2 channel expression was abolished in arterial smooth muscle cells of PKD2sm−/− mice, whereas PKD1, TRPC6, TRPM4, CaV1.2 or ANO1 proteins were similar to those in PKD2fl/fl controls. Telemetry demonstrated that systemic blood pressure was lower in PKD2sm−/− mice than in PKD2fl/fl controls. Experiments that measured cardiac function, plasma and urine electrolytes, plasma hormones and histological assessment of kidney structure identified no differences in PKD2sm−/− and PKD2fl/fl mice. Vasoconstriction stimulated by phenylephrine (PE), an α1‐adrenergic receptor agonist, and intravascular pressure were both attenuated in resistance‐size systemic arteries from PKD2sm−/− mice, when compared to PKD2fl/fl controls. PE‐induced non‐selective cation current (ICat) activation was smaller in systemic artery smooth muscle cells of PKD2sm−/− mice. Application of patch pressure activated single non‐selective cation channels in systemic artery smooth muscle cells of PKDfl/fl mice that were absent in cells of PKD2sm−/− mice. These data suggest that PE and intravascular pressure stimulate PKD2 channels in systemic artery smooth muscle cells, leading to vasoconstriction and an increase in blood pressure.

Support or Funding Information

NIH/NHLBI grants to Jonathan H. Jaggar. American Heart Association grants to Simon Bulley and M. Dennis Leo.
COMBINED EXERCISE TRAINING REDUCES BLOOD PRESSURE, ARTERIAL STIFFNESS, AND INSULIN RESISTANCE IN OBESE PREHYPERTENSIVE ADOLESCENT GIRLS
Authors: Karki Shakun , Son Won‐Mok , Seo Kook‐Eun , Park Song Young
Published: November 2023

Childhood obesity is strongly linked to pathological processes for cardiovascular diseases in adults. Obese adolescent girls with high blood pressure (BP) have been reported to have increased arterial stiffness, which is associated with the development of hypertension and atherosclerosis. The present study sought to examine the impact of combined resistance and aerobic exercise training (CRAE) on blood pressure (BP), brachial‐ankle pulse wave velocity (baPWV), insulin resistance (IR), and body composition in obese prehypertensive girls. Twenty girls (age, 15 ± 1 yrs; systolic BP, 132 ± 2 mmHg, diastolic BP, 80 ± 5 mmHg) were randomly assigned to a combined exercise group (EX, n=10) or a no exercise (CON, n=10). The EX group performed CRAE for 12 weeks, 3 times per week. BP, baPWV, blood nitrite/nitrate, endothelin‐1 (ET‐1), HOMA‐IR, and body composition were measured before and after the exercise intervention. BP (Δ−7.3 ± 2.67 mmHg), baPWV (Δ−1.23 ± 0.49 m/s), ET‐1 (Δ−14.35 ± 1.76 μmol/mL), nitrite/nitrate (Δ0.5 ± 0.09 μM), HOMA‐IR (Δ−1.4 ± 0.07), % body fat (Δ−1.35 ± 0.9%), and waist circumference were significantly improved (P<0.05) in the EX group after 12 weeks of training versus the CON. These findings indicate that 12 weeks of CRAE improves BP and HOMA‐IR prevents arterial stiffness, and the development of central adiposity in obese prehypertensive girls. Thus, this study provides evidence that CRAE can be a useful therapeutic treatment for high BP, IR and central adiposity which can also reduce the chances of pathological development for cardiovascular diseases in the adulthood.
The ankle‐brachial pressure index and it's correlation with oxidative stress in Acute Myocardial Infarction
Authors: Gulati Rajiv , Siddiqui Anwar Hasan , Parvez Anjum , Islam Najmul
Published: November 2023

Background

In recent years significant attention has been paid in identifying markers of increased cardiovascular risk, in particular the coronary artery disease. The ankle‐brachial pressure index (ABI), an easily accessible, inexpensive bedside test can be a significant tool to assess the vascular risk in symptomatic and asymptomatic cardiovascular patients. Oxidative stress and lipid peroxidation is thought to play a crucial role in the generation of atherosclerotic lesions of Acute Myocardial Infarction (AMI).

Objective

To determine the association between an abnormal ankle brachial index (ABI) and oxidative stress in coronary artery disease (CAD).

Method

The study population included 160 subjects divided in two groups, 90 patients with AMI and 70 age and sex matched healthy subjects as controls. Ankle Brachial Pressure Index (ABI) was measured in all the subjects along with their LDH level. Antioxidant status of the individuals was determined by measuring the serum levels of Glutathione Peroxidase (GPx) and Superoxide Dismutase (SOD). Estimation of Malondialdehyde (MDA), a marker of lipid peroxidation was used as a surrogate marker of free radical activity.

Result

A significantly low ABI (<0.9) was observed among the AMI patients as compared to healthy controls. Moreover the ABI showed negative correlation with the level of LDH amd MDA in the AMI patient. GPx and SOD were positively correlated with ABI.

Conclusion

ABI calculation would be able to identify more patients at high risk and as such it should be considered routine investigation for cardiovascular risk prediction.

Support or Funding Information

TRAVEL GRANT AND REGISTRATION GRANT FINANCIAL ASSISTANCE REQUIRED TO TRAVEL TO CHICAGO.

REQUEST TO ORGANIZERS TO PROVIDE ASSISTANCE.
Hydrogen Sulfide and Polysulfides Mimic the Effects of Hypoxia in Bovine Pulmonary and Porcine Coronary Arteries
Authors: Forgan Leonard George , DeLeon Eric , Gao Yan , Whiteman Matt , Olson Kenneth
Published: November 2023

The discovery of hydrogen sulfide (H2S) as an important biological signalling molecule has resulted in the elucidation of many complex biochemical and physiological functions of the molecule. One of its key physiological functions is the modulation of vascular tone. Our lab has shown potent effects of hypoxia on blood vessels from a wide range of craniates that is mimicked almost exactly by the application of exogenous H2S. Based on these data, we propose that H2S is a key transducer of hypoxia signalling and may be the elusive “oxygen sensor”. However, we hypothesise that some of the responses attributed to H2S may in fact be due to polysulfides (Sn) which form spontaneously upon dissolution. We hypothesised that vascular responses to H2S and polysulfides would mimic hypoxia responses in vascular smooth muscle. In the current study, we aimed to test this hypothesis by examining the effects of H2S, the mitochondrial H2S donor AP39 and polysulfides on isolated bovine pulmonary arteries and porcine coronary arteries. Paired vascular segments (with or without endothelium) were mounted inside Radnotti organ baths filled with Krebs‐Hanseleit Ringer (21% O2/5% CO2; 37°C). Vascular responses were recorded in response to hypoxia (1%) or cumulative doses of H2S (Na2S), K2Sn, H2S2, H2S3, H2S4 and AP39. Hypoxia caused a rapid and potent two‐phase constriction (50% of max) followed by dilation (25% of Max) of bovine pulmonary arteries. In contrast, hypoxia caused a small transient constriction (10% of max) followed by sustained dilation (30% of max) of porcine coronary arteries. Consistent with the effects of exogenous H2S application, K2Sn, H2S2, H2S3, H2S4 caused a constriction‐dilation in bovine pulmonary arteries of a similar magnitude to hypoxia responses. In contrast, AP39 caused a potent dilation only of pulmonary arteries. Application of all sulfides dilated porcine coronary arteries in a similar manner to hypoxia with responses also of a similar magnitude. Removal of the endothelium did not affect vascular responses in any preparation (P>0.05, F‐test). The current data support the hypothesis that H2S, and possibly polysulfides, act as an “oxygen‐sensor” in oxygen‐sensitive vessels since the physiological responses observed to hypoxia were mimicked by sulfide treatments. The data also suggest that polysulfides may be responsible for vasoactivity in response to exogenous H2S application. Future work will elucidate intracellular signalling events common to hypoxia and sulfide treatments on exposure to both H2S and polysulfides.
The Role of PPAR‐g in Shp1‐Mediated Regulation of Glucose Homeostasis in the Liver
Authors: Gomez Lilian , Lavallée‐Bourget Marie‐Hélène , Forest Marie‐Pier , Schwab Michael , Bellmann Kerstin , Sola‐Penna Mauro , Deshaies Yves , Marette André
Published: November 2023

The protein‐tyrosine phosphatase Shp1 plays a central role in high‐fat diet (HFD)‐induced insulin resistance. This enzyme, which negatively regulates insulin action on glucose homeostasis, is upregulated in metabolic tissues, such as liver, muscle and adipose tissue, of mice submitted to HFD. Hepatocyte‐specific Shp1 knockout mice (Ptpn6H‐KO) submitted to HFD develop hepatic steatosis but show less hepatic insulin resistance. These effects might be due to the observed attenuation of HFD‐induced inflammation and liver damage. Moreover, while Ptpn6H‐KO mice present a significant increase in PPARg expression, overexpression of Shp1 reduces the activity of this nuclear receptor. The aim of the present study is to evaluate the role of PPARg on the amelioration of liver inflammation in HFD‐fed Ptpn6H‐KO mice. For this, male Ptpn6H‐KO mice were kept on standard diet (SD) or HFD for 18 weeks. During the last 4 weeks the animals were treated with a very low dose of rosiglitazone, a known PPARg agonist. Rosiglitazone‐treated Ptpn6H‐KO mice showed an improvement in glucose tolerance without a significant change in insulinemia during oral glucose tolerance test. Insulin‐induced Akt phosphorylation, was increased by rosiglitazone in the Ptpn6H‐KO mice, which may partially explain the amelioration in glucose tolerance. Despite the fact that rosiglitazone increased hepatic steatosis in Ptpn6H‐KO mice, the drug also augmented the levels of the anti‐inflammatory cytokine, IL‐10. However, rosiglitazone did not improve the pattern of pro‐inflammatory cytokines in the liver. Altogether, our data support that Shp1 effects on glucose homeostasis involve the activation of PPARg, but the complete role of these players on liver inflammation has yet to be elucidated.

Support or Funding Information

Canadian Institutes of Health Research and CNPq
Endothelial cell‐specific knockout of epithelial sodium channel prevents vascular stiffening in response to a western diet in female mice
Authors: Aroor Annayya , Jia Guanghong , Manrique Camila , Lastra Guido , Barron Brady J , Dongqing Chen , Sun Zhe , Meininger Gerald A , Whaley‐Connell Adam T , Jaisser Frederic , Sowers James R
Published: November 2023

Arterial stiffening, a strong and an independent predictor of future cardiovascular events, has emerged as a therapeutic target for reduction of cardiovascular disease. Over‐nutrition/obesity predisposes individuals, particularly women, to arterial stiffening. We have recently developed a clinically relevant murine model of high fat and high fructose diet (western diet, WD) feeding which exhibits arterial stiffening associated with vascular and cardiac dysfunction. In this model, female mice have high plasma aldosterone levels and WD feeding increases mineralocorticoid receptor (MR) expression in the vasculature. One of the mechanisms by which MR activation promotes endothelial stiffness is through increased expression and activation of epithelial sodium channel (EnNaC) in endothelial cells (ECs). In this regard, we showed WD feeding was associated with increased expression of epithelial sodium channel in ECs (EnNaC) and prevention of WD induced aortic EC stiffness and impaired relaxation of the aorta by the administration of a very low dose of the EnNAC inhibitor, amiloride. In this study, we tested the hypotheses that specific deletion of EnNaC, decreases aortic EC stiffness and improves vascular relaxation in WD‐fed female mice. To produce cell specific deletion of the EnNaC gene,”floxed” EnNaC mice were serially crossed with Tie 2‐Cre transgene mice. This resulted in marked suppression of EnNaC expression in ECs. Female KO mice and littermate controls were fed a WD with excess fat (46%) and fructose (17.5%) for 12 weeks. Compared to mice fed a control diet (CD), aortic EC stiffness, measured ex vivo by AFM was significantly increased in WD‐fed mice and this was prevented in EnNaC KO mice fed a WD. The decrease in EC stiffness was associated with improvement in endothelial dependent aortic relaxation with acetylcholine. Taken together, these findings support the notion that a WD promotes ECMR activation of EnNaC in ECs and associated vascular stiffness which is a marker/predictor of cardiovascular disease.

Support or Funding Information

NIH (R01 HL73101‐01A and R01 HL107910‐01) and the Veterans Affairs Merit System (I01 BX001981) to JRS. K08HL129074‐01 to CM.
Diabetes Exacerbates Coronary Atherosclerosis in Ossabaw Miniature Swine with Metabolic Syndrome
Authors: Stivers Ben , Badin Jill , Kole Ayeeshik , Progar Victor , Pareddy Anisha , Alloosh Mouhamad , Sturek Michael
Published: November 2023

Over 35% of all US adults are estimated to have metabolic syndrome (MetS), which is defined as the presence of three or more of the following risk factors: obesity, hypertension, glucose intolerance, insulin resistance, and dyslipidemia. Furthermore, the incidence of type 2 diabetes is rapidly growing, often in an overlapping population. MetS and diabetes both substantially increase the risk of coronary artery disease (CAD), which continues to be the leading cause of death in the US. We investigated the extent to which diabetic hyperglycemia superimposed on MetS exacerbates CAD. We performed this study in the well‐characterized Ossabaw miniature swine model of MetS and CAD. The beta‐cell toxin alloxan was administered to swine by intravenous injection, then swine were placed in two groups: pigs that responded only transiently to alloxan thereafter having fasting normoglycemia (MetS, n=8) and those that responded to alloxan becoming permanently diabetic (MetS/D, n=8). After alloxan administration, swine were fed an atherogenic diet for six months to induce the MetS phenotype. At sacrifice, we used intravascular ultrasound (IVUS) imaging to quantify the extent of CAD by assessment of percent plaque burden and spotty calcification in the left anterior descending artery. Percent plaque burden quantifies the percentage of the area within the external elastic membrane (EEM) that is occupied by atherosclerotic plaque, using the formula (EEM area – lumen area)/EEM area*100%. The percent plaque burden was significantly greater in left anterior descending artery of the MetS/D swine compared to MetS swine (12.9% vs. 3.7%; p<0.05). Furthermore, this difference was more prominent in the proximal 15 mm of the artery (17.1% vs. 3.9%; p<0.05). We assessed coronary artery calcification by identifying echogenic signal stronger than adventitia and with acoustic shadowing peripheral to the calcium deposit. We calculated a calcium index for each artery using the formula (Frames with calcification/Total frames analyzed)*(Maximal arc angle of calcium/360°). The calcium index was significantly greater in the proximal 15 mm of the left anterior descending artery of MetS/D swine compared to MetS swine (0.0204 vs. 0.00003; p<0.05). These results show significant positive correlation with Von Kossa stained sections from the proximal 15 mm of each vessel and analyzed for calcified area (r=0.84). Thus, we conclude that CAD, as measured by plaque burden and presence of calcification by IVUS, is exacerbated when diabetes is superimposed on MetS.

Support or Funding Information

This work was supported by NIH T35 HL110854, P30 DK097512, the Fortune‐Fry Ultrasound Research Fund, and Eli Lilly & Co.
Effects of Cellular Dehydration on Glucose Regulation in Healthy Males ‐ A Pilot Study
Authors: Jansen Lisa T , Adams JD , Johnson Evan C , Kavouras Stavros A
Published: November 2023

Preliminary data from experimental animals have linked dehydration to glucose dysregulation via the action of vasopressin. Also epidemiological data suggest that humans with low water intake or elevated vasopressin are more prone to develop diabetes.

PURPOSE

Therefore, the purpose of this study was to investigate the effects of cellular dehydration on glucose regulation in healthy males.

METHODS

Four non‐diabetic males (28.4 y±1, HbA1c 5.6±0.2%, BMI 23.6±1.2kg·m−2) were recruited for this preliminary study. Each subject underwent two experimental trials, consisting of a 2 h intravenous infusion of saline (ISO 0.9% and HYP 3.0% of NaCl, 0.1ml·kg·min−1 infusion rate), followed by a 2h oral glucose tolerance test. Blood samples were taken from an antecubital intravenous catheter in 30min intervals.

RESULTS

Mean plasma osmolality was raised to 300±3mmol/kg for the HYP trial, while ISO maintained at 286± 2mmol/kg. Glycemic and insulin responses post glucose loading seemed to be delayed but spiked during HYP (150.6mg/dl glucose at min 60) while displaying a normal response during ISO (136mg/dl at min 60) trials. Homeostatic model assessment index of insulin resistance (HOMA IR) was HYP 0.93±0.24 vs. ISO: 0.85± 0.59, while Matsuda index of insulin sensitivity was HYP: 12.4±5.9 vs. ISO: 12.7±6.5. HYP seemed to cause increased insulin resistance and decreased insulin sensitivity compared to ISO.

CONCLUSION

The present data suggest that cellular dehydration induced by hypertonic saline infusion might be linked to glucose dysregulation in normal healthy adults.
Adipocyte‐specific deletion of HuR reduces diet‐induced obesity
Authors: Anthony Sarah R , Slone Samuel , Hui David Y , Owens Albert Phillip , Tranter Michael
Published: November 2023

Obesity is classified by the World Health Organization as one of eight principle causes of preventable chronic disease, and is directly associated with decreased life expectancy due to increased risk of type II diabetes, chronic respiratory disease, stroke, peripheral vascular disease, cancer, and cardiovascular disease. As a serious threat to human health, research into novel pharmaceutical targets and therapies to combat obesity is of growing interest to the scientific community.

Although the RNA‐binding protein HuR (Human antigen R) is highly expressed in adipocytes, its role in adipocyte function and adipocity is largely unknown. To conclusively determine the mechanistic role of HuR in adipocyte function, our laboratory has developed an adipocyte‐specific HuR knockout mouse (Adipo‐HuR−⁄−). These mice weigh less than wild‐type mice at baseline and have a reduced lean/fat body mass ratio. In addition, when placed on a chronic (22‐week) high fat diet (HFD, 60% kcal/fat), Adipo‐HuR−⁄− mice gain less weight compared to their wild‐type counterparts and display a decreased cold tolerance. Ongoing efforts to identify an underlying mechanism of action have shown no difference between wild‐type and Adipo‐HuR−⁄− mice following chronic HFD with regard to glucose tolerance or ratio of lean/fat body mass, but our data indicates a loss of UCP1 in the brown fat of Adipo‐HuR−⁄− mice.

Support or Funding Information

This work was partially funded by a University of Cincinnati Heart, Lung and Vascular Institute Near Horizons Collaborative Grant (MT, APO).