bluuebunny/crossref_metadata_2025 huggingface dataset:
Telemetric monitoring of blood flow and pressure in a chronic lamb model (862.7)
Authors: Fujji Yasuhiro , Centola Luca , Kinouchi Katsushi , Zhu Liqun , Pitsillides Koullis , Ferrier William , Talken Linda , Nasirov Teimour , Reinhartz Olaf , Riemer R. Kirk
Published: June 2021

The lamb is an excellent model for the study of cardiopulmonary dynamics in small children. Steady state measurements of cardiovascular parameters such as blood pressure and blood flow in undisturbed subjects are challenging to acquire but essential in the continuous monitoring of cardiopulmonary and systemic interactions. We have established a chronic lamb model that incorporates a telemetry system (Transonic EndoGear Inc, Davis CA) capable of measuring up to five variables in the same animal. This provides a new opportunity to record uninterrupted comprehensive cardiovascular performance over an extended period of time. This telemetry system uses a Doppler‐based flowmeter that allows measurements of flow velocity using endo‐, epi and peri‐vascular mounted flowprobes. Blood pressure is measured with endovascular 3F solid‐sate pressure catheters. With this system, we have applied perivascular Doppler flowprobes in the superior vena cava, endovascular flowprobes in the main pulmonary artery and epivascular flowprobes on the aorta as well as endovascular blood pressure catheters in the left internal mammary artery, main pulmonary artery, and right atrium. The EndoGear system enables the chronic invasive monitoring of critical cardiovascular variables in untethered and unrestrained lambs for extended periods, providing new insight about the time course of postnatal pulmonary vascular adaptation.
Short‐term muscle disuse atrophy is not associated with increased skeletal muscle lipid accumulation or impaired oxidative enzyme activity in young or old men (863.1)
Authors: Wall Benjamin , Dirks Marlou , Snijders Tim , Stephens Francis , Senden Joan , van Loon Luc
Published: June 2021

Aging is accompanied by a loss of skeletal muscle mass (sarcopenia) and metabolic function. A period of disuse (e.g. injury/illness) also causes muscle atrophy. The accumulation of periods of disuse throughout the lifespan has been proposed as a key factor in the development of sarcopenia. However, it is unknown whether brief periods of disuse also impair muscle metabolic function. We investigated the effects of 5 days of limb immobilization in healthy young (n=12; 23±1 y) and old (n=70±1 y) men on intramyocellular triacylglycerol (IMTG) content, the maximal activity and activation status of selected mitochondrial enzymes and the mRNA expression of genes associated with mitochondrial biogenesis, in muscle biopsies taken before and after disuse. At baseline, IMTG content was greater in old compared with young men (56.3±6.8 and 34.8±7.3 µmol.g‐1, respectively; P<0.05) but no changes were observed following immobilization. Disuse did not reduce muscle citrate synthase, β‐HAD or cytochrome C oxidase activity. However, muscle pyruvate dehydrogenase complex activation status increased following immobilization in the elderly men. The muscle mRNA expression of PGC1α and citrate synthase declined following immobilization in both groups. We conclude that 5 days of muscle disuse is not accompanied by a net increase in muscle lipid deposition or a decline in muscle oxidative capacity in young or elderly men.
Role of phosphodiesterase‐1 in muscarinic receptor‐induced human urinary bladder smooth muscle excitability and contractility (865.4)
Authors: Xin Wenkuan , Li Ning , Rovner Eric , Cheng Qiuping , Petkov Georgi
Published: June 2021

Role of phosphodiesterase‐1 in muscarinic receptor‐induced human urinary bladder smooth muscle excitability and contractility Wenkuan Xin1, Ning Li1, Eric S. Rovner2, Qiuping Cheng1, and Georgi V. Petkov1,2
1Drug Discovery & Biomedical Sciences, South Carolina College of Pharmacy, University of South Carolina, Columbia, SC 29208 and 2Medical University of South Carolina, Charleston, SC 29425 Activation of muscarinic M3 receptors (M3Rs) leads to an inhibition of the large conductance Ca2+‐activated K+ (BK) channels and an increase in human urinary bladder smooth muscle (UBSM) excitability. M3R‐mediated Ca2+ influx activates phosphodiesterase‐1 (PDE1) and reduces cellular cAMP levels. We investigated the mechanism by which the integrated PDE1 and MR signaling pathways stimulate human UBSM excitability and contractility. Pharmacological activation of M3Rs with carbachol (1 µM) decreased the frequency and amplitude of transient BK currents (TBKCs) in UBSM cells and subsequent inhibition of PDE1 with 8MM‐IBMX (10 µM) recovered TBKC activity. In the absence of M3R stimulation, inhibition of PDE1 increased TBKCs frequency, and subsequent inhibition of protein kinase A (PKA) with H‐89 (10 µM) reduced TBKCs frequency. 8MM‐IBMX (10 µM) hyperpolarized UBSM membrane potential, an effect which was blocked upon PKA inhibition. 8MM‐IBMX suppressed spontaneous phasic contractions and nerve‐evoked contractions of UBSM isolated strips. In conclusion, PDE1 enhances the M3R‐mediated inhibition of BK channels. Inhibition of PDE1 attenuates UBSM excitability by increasing BK channel activity via a PKA‐dependent mechanism. A combination of a PDE1 inhibitor and a MR antagonist can be an effective novel approach for the treatment of bladder overactivity.

Key words: phosphodiesterase, muscarinic receptor, detrusor

Grant Funding Source: NIH R01 DK084284 to Georgi V. Petkov
Prostaglandin E2 inhibits the large‐conductance voltage‐ and Ca2+‐activated K+ channels in guinea pig urinary bladder smooth muscle (865.7)
Authors: Parajuli Shankar , Provence Aaron , Petkov Georgi
Published: June 2021

Prostaglandin E2 (PGE2) is an important signaling molecule that has been shown to be involved in the regulation of urinary bladder smooth muscle (UBSM) contractility in both rodents and humans. However, the underlying mechanism by which PGE2 evokes UBSM contractions is not well understood. Here, we investigated whether large conductance voltage‐ and Ca2+‐activated K+ (BK) channels mediate the stimulatory effects induced by PGE2 on guinea pig UBSM contractility. We used a combined experimental approach including patch‐clamp electrophysiology, live‐cell Ca2+ imaging, and isometric UBSM tension recordings to investigate BK channel regulation by PGE2 at both cellular and tissue levels. PGE2 increased the spontaneous phasic contractions of UBSM isolated strips in a concentration‐dependent manner (10 nM‐10 µM). BK channel inhibition with paxilline attenuated the PGE2‐induced UBSM phasic contractions, suggesting that BK channels are among the targets of PGE2. Our data also indicate that PGE2 (10 µM) caused an inhibition of the amplitude and frequency of spontaneous transient BK currents and increased the intracellular Ca2+ levels in freshly‐isolated UBSM cells. Thus, for the first time we have revealed a novel mechanism by which BK channels mediate the PGE2 stimulatory effects on guinea pig UBSM contractions.

Grant Funding Source: Supported by NIH R01 DK084284 grant to Georgi V. Petkov.
Associations of plasma osteocalcin and fetuin‐A with bone mineral density in post‐menopausal women (867.16)
Authors: Hunter Larry , Farr Joshua , Miller Virginia
Published: June 2021

In postmenopausal women, decreases in estrogen disrupt the normal balance of bone turnover, increasing bone resorption relative to bone formation. This study investigated the effects of menopausal hormone treatment (MHT) on volumetric bone mineral density (vBMD) and markers of bone turnover in plasma of healthy, recently‐menopausal women. Women (age 52.3±2.3 yrs; n=115) enrolled in the Kronos Early Estrogen Prevention Study (KEEPS) were randomized to either: oral conjugated equine estrogen (oCEE), transdermal 17β estradiol (tE2) each with intermittent oral micronized progesterone or placebo (Pl), for 48 months. vBMD was assessed by quantitative computed tomography of the wrist, and plasma levels of osteocalcin (OCN; a bone turnover marker), and of Fetuin‐A, a hepatocyte‐derived modulator of osteogenesis, were quantified by ELISA. At 48 months, cortical vBMD at the distal radius had decreased by 2.9% in the Pl group, correspondent with an increase above initial plasma OCN (15.0 ng/ml) of 38.5%. MHT attenuated the vBMD decrease (0.9% in both treatment groups combined; P=0.015), and the OCN increase (8.8 and 4.3% in oCEE and tE2, respectively). Plasma Fetuin‐A levels did not differ significantly among groups at 48 mo. Unexpectedly, Fetuin‐A was negatively associated (r=‐0.50 to ‐0.62; P <0.05) with changes in trabecular bone microarchitectural parameters at the distal radius in the Pl group, whereas both oCEE and tE2 attenuated this effect (all P‐values >0.05). As expected, MHT attenuated bone turnover in postmenopausal women. However, the relationship between processes regulated by OCN and Fetuin‐A require further evaluation.

Grant Funding Source: Supported by Aurora Foundation, HL90639 and AG44170
Nitric oxide inhibits vascular remodeling by decreasing angiotensin II‐induced RhoA translocation to caveolae and ROS formation (867.6)
Authors: Hajj Hussein Inaya , Nourddine Ward , Soudani Nadia , Zeidan Asad
Published: June 2021

Decreased production of nitric oxide (NO) leads to induce vascular smooth muscle cell (VSMC) hypertrophy via angiotensin II (AngII) receptors. However, the regulatory mechanism of NO activity on Ang II‐mediated VSMC remodeling remains fully unclear. Here we hypothesized that caveolin‐1 (cav1) and NO production are involved in the regulation of AngII‐induced VSMC remodeling via inhibition of the RhoA translocation to caveolae. Rat aortic rings were cultured in the presence of AngII (1 nM) with or without the NO donor S‐nitroso‐nacetylpenicillamine (100 μM; SNAP), the ROCK inhibitor (10 μM; Y‐27632), the RhoA inhibitor C3 exoenzyme (3 ng/ml; C3), or methyl‐B‐cyclodextrin (10 mM; MBCD). AngII‐induced VSMC hypertrophy and protein synthesis were inhibited by pre‐treatment with SNAP, Y‐27632, C3 or MBCD. AngII‐induced protein synthesis was associated with increased in ROS formation and expression of cav‐1 (2 folds), NADPH oxidase1 (NOX1; 4 folds) and NOX3 (5 folds) and decreased NOX2 (2 folds) expression and NO activity (3 folds).

Treatment of the aortic ring with AngII for 20 min increased caveolae‐bound RhoA (4‐folds), cofilin‐2 phosphorylation (3 folds), and F‐ to G‐actin ratio (2 folds), which were prevented by increased of NO production. These results will allow for the creation of pharmacological agents for the treatment of vascular hypertrophy due to AngII.
miR‐133a alleviates cardiac autophagy by targeting AMPK in Ins2+/‐ diabetic mice (868.3)
Authors: Nandi Shyam , Mishra Paras
Published: June 2021

Optimum level of autophagy is indispensable for survival and cellular function, and miRNA tightly regulates biological functions. In diabetic hearts, miR‐133a (anti‐hypertrophy and anti‐fibrosis) is attenuated and autophagy is induced. Based on these observations, we hypothesize that inhibition of miR‐133a induces autophagy in diabetic hearts. To test the hypothesis, HL1 cardiomyocytes were treated with low (LG‐5mM) and high (HG‐25mM) dose of D‐glucose, and miR‐133a and scrambled control. To determine whether miR‐133a mitigates autophagy in diabetic hearts, we measured the levels of monodansylcadaverin intensity (marker of autophagolysosome) and then the upstream targets ATG3, LC3B (autophagophore formation) and Beclin‐1 (initiator of autophagy signaling). We also determined the activity and expression of mTOR (upstream inhibitor of Beclin‐1) and AMPK (upstream inhibitor of mTOR) by RT‐qPCR, immunoblotting and immunofluorescence. The specific role of miR‐133a in mitigation of high glucose mediated autophagophore formation is determined by transfecting HL1 cardiomyocytes with LC3‐RFP plasmid. In hyperglycemic cardiomyocytes, miR‐133a decreases the protein levels of AMPK (4.1±0.38 fold), that in turn increases mTOR (3.2±0.4 fold), which suppresses Beclin1 (2.5± 0.33 fold) and the downstream targets LC3B (3.5±0.4 fold) and ATG3 (2.5±0.18 fold), and fluorescent intensity of monodansylcadaverin (2.5±0.47 fold). The in vivo studies were performed on C57BL/6J and Ins2+/‐ (spontaneous, chronic T1D) mice. Both groups of mice were treated with miR‐133a mimic (10^5lentivirus, iv,/day for 5 days) and hearts were extracted after 10 days. The in vivo results corroborate that miR‐133a mitigates cardiac autophagy in diabetes. Further investigation revealed that AMPK 3’UTR is a direct target of miR‐133a. These findings demonstrate a novel mechanism of miR‐133a mediated mitigation of autophagy in diabetic hearts.

Grant Funding Source: NIH grants: HL113281 and HL116205.
Unilateral diaphragm muscle paralysis minimally impacts ventilation in rodents (871.5)
Authors: Sieck Gary , Gransee Heather , Gill Luther , Jorgenson Amy , Medina Juan , Alvarez‐Argote Juliana , Mantilla Carlos
Published: June 2021

Ventilatory behaviors across a range of species including humans require less than 50% of maximal force‐generating capacity by the diaphragm muscle, the main inspiratory muscle in mammals. Near maximal forces are only generated during expulsive behaviors usually associated with airway clearance. There is ongoing controversy regarding the impact of unilateral lesions (e.g., spinal cord injury, denervation) on ventilatory outcomes. We hypothesized that unilateral denervation of the diaphragm muscle in rats and mice would minimally impact ventilation. Transdiaphragmatic pressure (Pdi) measurements were used to estimate diaphragm muscle force in adult male rats and mice. Following acute, unilateral phrenic nerve transection in the neck, there was no change in Pdi during eupnea or hypoxia‐hypercapnia in rats or mice. Reduced Pdi was evident during deep breaths and tracheal occlusion (behaviors associated with ~70% of maximal Pdi elicited by bilateral phrenic nerve stimulation) in both species. These results are also consistent with the lack of changes in tidal volume or respiratory pattern during eupnea measured by whole body plethysmography in unrestrained, spontaneously breathing rats after mid‐cervical contusion or hemisection injuries. These results highlight the large reserve capacity for force generation by the diaphragm muscle in rodents and the importance of measuring multiple motor behaviors.

Grant Funding Source: Supported by HL096750, AG044615, HL105355 and Mayo Center for Regenerative Medicine
Peripheral chemoreceptors determine the respiratory sensitivity of central chemoreceptors to CO2: role of carotid body CO2 (872.3)
Authors: Smith Curtis , Henderson Kathleen , Dempsey Jerome
Published: June 2021

We have shown previously that inhibition of the isolated carotid body (CB) chemoreceptor (via CB‐specific hyperoxia & hypocapnia) markedly reduced the ventilatory response sensitivity of the central chemoreceptors to increased PaCO2 whereas stimulation (via CB‐specific hypoxia & normocapnia) markedly increased it (Blain et al., J. Physiol. 588: 2455‐2471, 2010). These findings were consistent with ventilatory hyperaddition of the CB and central chemoreceptors. We questioned whether changes in CB CO2 alone would result in similar interaction. To date, we have tested this in 4 unanesthetized and chronically instrumented dogs in which the CBs were isolated & perfused independently of the systemic circulation. CB hypocapnia (PcbCO2 ~ 20 mmHg < eupnea; PcbO2 normal) and CB hypercapnia (PcbCO2 ~ 20‐30 mmHg > eupnea; PcbO2 normal) were used to inhibit/stimulate the CB while systemic (and therefore central chemoreceptor) PCO2 was increased with 3 different levels of FICO2 in a normoxic background. We found that CB hypocapnia decreased (mean slope 34% of control), and CB hypercapnia increased (mean slope 125% of control), the ventilatory response of the central chemoreceptors to CO2. Our preliminary conclusion is that the hyperadditive CB/central interaction reported previously is independent of the stimuli used to inhibit/stimulate the CB.

Grant Funding Source: Supported by NIH, NHLBI HL50531
Purinergic signaling contributes to CO2‐sensitivity of neurons in the retrotrapezoid nucleus but not nucleus of the solitary tract or medullary raphe (872.6)
Authors: Wenker Ian , Poss Erin , Sobrinho Cleyton , Ana Takakura , Moreira Thiago , Mulkey Daniel
Published: June 2021

Central chemoreception is the mechanism by which the brain controls breathing in response to changes in tissue CO2/H+. Several brainstem regions are thought to contribute to chemoreception including the caudal nucleus of the solitary tract (cNTS), medullary raphe and retrotrapezoid nucleus (RTN). Although the molecular basis of chemoreception remains unclear, evidence suggests that RTN chemoreception involves intrinsic H+ sensing by an unidentified K+ channel and purinergic signaling possibly from CO2‐sensitive astrocytes. However, it is not clear whether purinergic signaling influences CO2‐responsiveness of other putative chemoreceptors. The goal of this study is to determine whether purinergic signaling modulates basal activity or CO2‐responsivness of neurons in the cNTS or medullary raphe. We use cell‐attached current clamp techniques to characterize firing rate responses to 15% CO2 and focal application of ATP (1mM) under control conditions and in the presence of a P2‐receptor blocker (PPADS, 100 µM). Chemosensitive neurons in the cNTS or medullary raphe were identified in brain slices (300 µm thick) from neonatal rat pups (P7‐12) bases on a 蠅 0.5 Hz firing rate response to 15% CO2. We found that CO2‐sensitive neurons in the cNTS, but not the medullary raphe, respond to focal ATP application with ~3 fold increase in firing rate. However, bath application of PPADS had no effect on baseline activity or CO2‐responsivness of neurons in either region. Immunohistochemical analysis using an astrocyte‐specific marker (aldehyde dehydrogenase 1L1) suggests that the RTN has a higher density of astrocytes compared to the cNTS or medullary raphe. Together, these results suggest that purinergic signaling is a unique feature of RTN chemoreception.

Grant Funding Source: Supported by NLBI (HL 104101) and AHA (11PRE7580037)
Lipopolysacchride exposure in newborn rats increases mast cell infiltration in the carotid body and attenuates hypoxic chemosensitivity (873.9)
Authors: Master Zankhana , Kesavan Kalpashri , Mason Ariel , Chavez‐Valdez Raul , Shirahata Machiko , Gauda Estelle
Published: June 2021

Inflammation adversely modifies carotid body (CB) structure and chemosensitivity in adult animals[1] . Since newborn infants are vulnerable to infections and have unstable breathing, we determined the effect of inflammation on the CB structure and function in newborn rat pups. Pups were given LPS (0.1mg/kg; IP) or saline at postnatal day 2 (P2). Histological sections of the CB were examined for inflammatory cells at P4 (n=7) and P9‐12 (n=6). After LPS exposure, only mast cells were seen, often encircling the CB, and clustered within the CSN as it entered the CB. Mast cells per section (mean±SEM) was higher at P9‐12 in LPS (7.4±1.5) vs saline (5.4±1.4) exposed animals (p=0.04). Surprisingly, more mast cells were seen at 7‐10 days vs 48hrs after LPS exposure. At P21 we also measured carotid sinus nerve (CSN) activity in vitro, in superfused preparations (preps) from LPS (n=8) and saline (n=8) exposed animals. LPS exposure attenuated the peak hypoxic response. In response to hypoxia, CSN (impulses/sec) increased in both groups, but peaked and plateaued at 4 mins vs 6 mins in preps from LPS and saline exposed animals, respectively. Mast cells release pro and anti‐inflammatory cytokines, growth factors, tryptase, and neuromodulators which modify the microenvironment and sensitivity of sensory neurons. Inflammation induces mast cell infiltration in the CB and may attenuate hypoxic chemosensitivity several weeks after the initial inflammatory event during early postnatal development.
Arterial pressure and gene expression in the nucleus of the solitary tract in rats fed with high‐fat diet (874.4)
Authors: Speretta Guilherme , Bassi Mirian , Ruchaya Prashant , Sumners Colin , Menani José , Colombari Eduardo , Colombari Débora
Published: June 2021

The aim of this study was to evaluate the mean arterial pressure (MAP) and gene expression of components of the renin‐angiotensin system (RAS) and pro‐inflammatory cytokines in the nucleus of the solitary tract (NTS) in rats fed with high‐fat diet (HFD). Male Holtzman rats (300‐320 g, n = 6/group) were fed with either standard chow diet (SCD; 5.4% total fat) or HFD (26.4% total fat) for 3 or 6 weeks before MAP recording, baroreflex tests and brains being harvested for RT‐PCR. HFD for 3 (HFD3) or 6 weeks (HFD6) increased MAP (HFD3: 114 ± 2, vs. SCD3: 105 ± 1 mmHg; HFD6: 116 ± 2, vs. SCD6: 107 ± 1 mmHg, p < 0.05). HFD6 also impaired the baroreflex (HFD6: ‐2.27 ± 0.32, vs. SCD6: ‐2.90 ± 0.15 bpm/mmHg, p < 0.05). HFD3 increased ACE mRNA expression in the NTS (HFD3: 2.78 ± 0.33, vs. SCD3: 1.00 ± 0.26, p < 0.05), without changing the levels of AT1R, TNF‐α and IL‐6 mRNAs. Conversely, HFD6 decreased ACE mRNA levels in the NTS (HFD6: 0.27 ± 0.06, vs. SCD6: 1.11 ± 0.12, p < 0.05), and increased the levels of mRNAs for AT1R (HFD6: 2.74 ± 0.35, vs. SCD6: 1.07 ± 0.25, p < 0.05), TNF‐α (HFD6: 3.00 ± 0.90, vs. SCD6: 1.10 ± 0.17, p < 0.05) and IL‐6 (HFD6: 2.73 ± 0.76, vs. SCD6: 1.08 ± 0.10, p < 0.05) in the NTS. These results suggest that HFD may activate pro‐inflammatory cytokines and modify RAS components in the NTS, whose expression differs based on the period of the HFD. These factors may contribute to the increase in MAP and the impairment of the baroreflex produced by HFD.

Grant Funding Source: CAPES, FAPESP, FAPESP/PRONEX
Synaptic plasticity of GABAergic circuitry in the RVLM during Ang II‐dependent malignant hypertension (874.6)
Authors: Derbenev Andrei , Gao Hong , Miyata Kayoko , Mitchell Kenneth , Zsombok Andrea
Published: June 2021

The rostral ventrolateral medulla (RVLM) is a critical component of the sympathetic nervous system (SNS) mediating regulation of cardiovascular function, including arterial blood pressure (ABP). It has been shown that decreased inhibition of RVLM neurons increases SNS activity and thereby elevates ABP. However, very little is known about the control of this region of the brain in hypertensive states; in particular, in transgenic rats [TGR(Cyp1a1Ren2)] with inducible Ang II‐dependent malignant hypertension. In the present study we used the transsynaptic retrograde viral tracer, PRV‐152 to identify preautonomic neurons in the RVLM. We found that chronically (8 days) increased plasma Ang II levels significantly potentiate glutamatergic and decrease GABAergic synaptic transmission. Moreover, our data revealed significantly reduced amplitude of inhibitory GABAA‐mediated extrasynaptic tonic current in the RVLM neurons. The results of our study demonstrate that GABAergic activity is decreased in the RVLM of Cyp1a1‐Ren2 transgenic rats with Ang II‐dependent malignant hypertension. These compelling data demonstrate synaptic plasticity in the RVLM in Ang II‐dependent hypertension.

Grant Funding Source: NIH P30GM103337
Effect of beta‐adrenergic blockade on coronary blood flow during isometric exercise in older adults (875.7)
Authors: Ross Amanda , Gao Zhaohui , Heffernan Matthew , Leuenberger Urs , Sinoway Lawrence , Muller Matthew
Published: June 2021

The rise in heart rate (HR) and cardiac contractility during exercise is due to activation of myocardial β‐adrenergic receptors. In animals, β‐adrenergic receptors in the coronary vasculature also mediate a parallel increase in coronary blood flow. However, the role of β‐ adrenergic receptors in the human coronary circulation is unknown. We hypothesized that β‐adrenergic blockade with propranolol would attenuate reflex tachycardia and coronary hyperemia in response to isometric handgrip in healthy older adults. Six men (66 ± 2 yrs) performed isometric handgrip exercise at 40% of maximal voluntary contraction for 2 minutes after receiving intravenous propranolol or no treatment. HR and blood pressure were monitored continuously and rate‐pressure product (RPP) was calculated as an index of myocardial oxygen demand. Coronary blood flow velocity (CBV) was measured by transthoracic Doppler echocardiography and coronary vascular resistance (CVR) was calculated. The coronary supply to demand ratio was calculated as CVR/RPP. Propranolol decreased the HR (8 ± 3 vs. 4 ± 1) and RPP (2580 ± 612 vs. 1520 ± 163) responses to exercise but augmented the CVR/RPP response (‐0.24 ± .09 vs. ‐0.49 ± 0.15). Mean arterial pressure, CVR and CBV were unaltered. β‐adrenergic blockade not only decreased myocardial oxygen demand in response to exercise, it also improved oxygen supply.

Grant Funding Source: Supported by NIH P01 HL096570 and UL1 TR000127
Central administration of IL‐1 receptor antagonist increases vasopressin secretion in late phase of sepsis in rats (876.7)
Authors: Wahab Fazal , Tazinafo Lucas , Batalhão Marcelo , Carnio Evelin , Rocha Maria
Published: June 2021

Clinical and experimental studies have reported that the initial phase of sepsis is characterized by elevated plasma vasopressin (AVP) concentrations. However, in the late phase, despite of the significant decrease in the arterial pressure, the AVP secretion decrease and the plasma concentrations remain unusually low, contributing to the hypotension, vasodilator shock, and death. Considering the role of AVP in the vasopressor response, the elucidation of the mechanisms of this deficient hormone secretion may contribute to therapy during sepsis.

The aim of this study was to analyze the effect of IL‐1ra (an Interleukin‐1 receptor antagonist) on sepsis‐induced alterations in plasma AVP and NO, and cerebrospinal fluid (CSF) NO levels. After Wistar rats were intracerebroventricullary injected with 2 ul of IL‐1ra (9 nmol/ or vehicle (PBS 0.01M) sepsis was induced by cecal ligation and puncture (CLP). Blood samples were collected from different groups of rats (n=6‐8/group) by decapitation after 4‐, 6‐ and 24‐h. Specific ELISA and Chemiluminescence assays were used for measurement of AVP and NO concentrations, respectively. All experiments were carried out according to an institutional ethical committee approved protocol.

IL‐1ra administration did not alter plasma vasopressin after 4‐ and 6‐h as compared to vehicle in CLP animals. In contrast, after 24‐h AVP levels were significantly (P<0.01) higher in IL‐1ra treated animals as compared to vehicle treated animals. IL‐1ra administration significantly (P<0.01) decreased NO concentration in CSF but not in plasma. Moreover, the survival rate of IL‐1ra treated rats increased by 38% in comparison to vehicle administered animals.

In conclusion, the central administration of IL‐1ra increases AVP secretion in the late phase of sepsis which was beneficial for survival. We believe that one of the mechanisms for this effect of IL‐1ra is through reduction of NO concentration in CSF of the septic rats.
Recovery of neural signaling following oxygen glucose deprivation is greater in Syrian hamster hippocampi than in rat hippocampi (877.10)
Authors: Mack Jacob , Mikhailova Alexandra , Hamilton Jock , Horowitz John , Horwitz Barbara
Published: June 2021

Previous studies showed that neurons in mammalian obligatory hibernators are less damaged by oxygen glucose deprivation (OGD) than those of non‐hibernating species. But it is unknown if recovery of hippocampal signal processing after transient OGD is greater in facultative hibernators (e.g., Syrian hamsters) than in rats (non‐hibernators). We tested the hypotheses that 30 min after OGD exposure, recovery would be greater: (1) at low vs. high temperatures in both species and (2) in hamsters vs. rats. Following Schaffer collateral stimulation, evoked responses from CA1 neurons were measured at 25oC, 30oC, and 35oC. A 15 min baseline response was recorded for slices perfused in oxygenated artificial cerebrospinal fluid (O2aCSF). Perfusate was then switched to aCSF minus glucose and gassed with nitrogen (OGD) for 10 min, after which it was returned to O2aCSF for 30 min. Degree of recovery from OGD was significantly greater (P<0.05) at lower temperatures in hamster and rat slices, supporting hypothesis 1. Additionally, at 25oC, hamster slice recovery (108%; n=19 slices) was significantly greater (P<0.05) than that of rat slices (80%; n= 16). The same was true at 30oC (93% for 19 hamster slices vs. 49% for 18 rat slices), consistent with hypothesis 2. No significant species differences were seen at 35oC. Understanding naturally occurring tolerance to OGD in hibernators may lead to new strategies mitigating stroke damage.

Grant Funding Source: JM was supported by an American Physiological Society UGSRF award.
Recovery of synaptic transmission from oxygen glucose deprivation in Syrian hamster hippocampi is temperature dependent and enhanced in hibernation (877.11)
Authors: Mikhailova Alexandra , Hamilton Jock , Horowitz John , Horwitz Barbara
Published: June 2021

It is not known if recovery of signal processing following transient oxygen glucose deprivation (OGD) is greater in hippocampal slices from hibernating hamsters (HH) than in slices from nonhibernating euthermic hamsters (EU). We hypothesized that HH slices recover synaptic transmission more completely than do EU slices, and that decreased temperature further enhances recovery. To test these two hypotheses, evoked response amplitudes (ERAs) of CA1 neurons to afferent stimulation were measured during a 15 min control period [slices perfused with oxygenated artificial cerebrospinal fluid (O2 aCSF, 10 mM glucose)], followed by OGD treatment (perfusate switched to aCSF gassed with nitrogen and no glucose) for 10 min, and a 30 min recovery period (slices returned to O2 aCSF, 10 mM glucose). At 35°C, 10 min after OGD treatment, HH ERAs had recovered to 65.7 ± 12.6% (n=9) of control while EU ERAs had recovered to 22.9 ± 8.0% (n=17; P<0.05). Lower slice temperatures (25°C and 30°C) were neuroprotective for both HH and EU, while the hibernating state afforded no additional neuroprotection. These data support our hypotheses that HH slices are more tolerant to OGD than are EH slices, that decreased temperatures further enhance protection in both HH and EH slices, and suggest that preparation for hibernation induces neuroprotective mechanisms in this facultative hibernator.

Grant Funding Source: Supported by UC Davis Provost's Undergraduate Fellowship to AM
Can cold‐induced cardiac activity prevent cardiac pathologies caused by obesity? (881.12)
Authors: Barnhill Spencer , Schaeffer Paul
Published: June 2021

The purpose of this study is to investigate the idea that prolonged cold exposure, which mimics the increased demand of exercise, can prevent the early effects of pathological cardiac hypertrophy caused by obesity in mice. Given that exercise has reduced detrimental effects of hypertrophic cardiomyopathy, we hypothesized that prolonged cold exposure may act similarly. We investigated three groups of mice at three months of age. The groups were wild‐type mice fed a standard chow diet (CON), transgenic UCP‐dta mice fed a high‐fat diet (Obese), and cold exposed transgenic UCP‐dta mice fed a high‐fat diet (Cold‐Obese). Both Obese and Cold‐Obese mice showed higher cardiac weight compared to CON. Gene expression analysis showed little to no up‐regulation of pathological hypertrophy markers in Obese and Cold‐Obese mice. Further analysis showed down‐regulation of several metabolic genes in Obese mice and maintenance or up‐regulation of those genes in Cold‐Obese mice. Echocardiography and cardiac catheterization suggested healthy left ventricular pressures but mild diastolic dysfunction in the Cold‐Obese mice. Metabolic profiles suggested improvements in cardiac metabolism while functional analyses showed cold exposure may lead to cardiac dysfunction in Cold‐Obese mice.

Grant Funding Source: Supported by NIH #1R15DK085497–01A1 to PJS
Combined strength and endurance training does not improve left ventricular systolic function in response to a high‐intensity exercise in females (881.7)
Authors: Dumanoir Greg , Haykowsky Mark , Taylor Dylan , Syrotuik Dan , Bell Gordon
Published: June 2021

The acute effect of high‐intensity exercise combined with strength and endurance training on left ventricular (LV) systolic function in female rowers is not well known. The objective of this study was to evaluate the effects of 10‐weeks of endurance and strength training on maximal oxygen uptake (VO2max), endurance performance, strength, and LV morphology and systolic function in eight female rowers (mean age: 25 ± 9 years). LV systolic function was also assessed before and immediately after completing a high‐intensity endurance performance test (2000m of rowing). Ten‐weeks of combined strength and endurance training significantly improved VO2max (before vs. after; 2.7 ± 0.4 vs. 3.0 ± 0.3 L/min), endurance performance time (510 ± 41 vs. 491 ± 24 sec), leg press (163 ± 45 vs. 235 ± 86 kg) and bench press (40 ± 4 vs. 46 ± 5 kg) one repetition maximum strength. Combined training did not change end‐diastolic cavity area (19 ± 3 vs. 19 ± 4 cm2), end‐systolic cavity area (9 ± 2 vs. 8 ± 2 cm2), fractional area change (51 ± 6 vs. 55 ± 3%) or mass (160 ± 34 vs. 159 ± 17 g). High‐intensity exercise was associated with an increase in contractility and fractional area change from before to after training. In conclusion, 10 weeks of rowing and strength training in female rowers improves exercise capacity, endurance performance and muscle strength without altering LV morphology. In addition, combined strength and endurance training was not associated with an increase in LV systolic function but contractility and fractional area was significantly increased with high intensity exercise.

Grant Funding Source: Supported by the Sport Science Association of Alberta
Twelve weeks of community exercise improves health parameters in women living in a semi‐rural township in South Africa (884.25)
Authors: Brooks Naomi , Bowes Jenna , Gava Lucia , January Nosiviwe , Esterhuizen Annali , Myburgh Kathryn
Published: June 2021

Cardiovascular disease (CVD) is the second highest leading cause of death in South Africa. The aim of this study was to instigate and complete a 12 wk exercise program in an African semi‐rural township and to assess its impact on body composition, blood pressure (BP) and lipid profile. Women (n=18) with average age 41(2) yr were recruited and measurements taken before and after 12 wk of exercise to determine: Waist:Hip ratio(W:H), systolic and diastolic BP (SBP; DBP), and lipid profiles including cholesterol, high and low density lipoproteins (HDL; LDL) and triglycerides (all mmol/L). Values are Mean(SE). The 12 w exercise program had no significant effect on body mass index: 31(2) to 30(2) kg/m2, but W:H ratio tended to decrease: 0.82(0.02) to 0.79(0.01) [p=0.059]. SBP was significantly reduced after exercise [137(5) to 127(4) mmHg; p=0.03], but not DBP. Total cholesterol levels declined from 4.5(0.2) to 4.2(0.2) (p=0.03). In conclusion, a community based exercise programme is feasible in obese women living in the township. Improvements in blood pressure, cholesterol levels and body composition are beneficial for improving individual health and reducing the risk of CVD.
Game time environmental conditions and concussion rate in college football (884.28)
Authors: Harwood J. , Pennetti Alex , Milne Kevin
Published: June 2021

A central function of cerebrospinal fluid (CSF) is to limit brain impact against the bony interior surface of the skull during jarring movements. Dehydration of approximately 2% of total body volume can reduce CSF volume by 10%. In prolonged competition, especially in hot, humid conditions, athletes commonly reach or exceed this level of dehydration, potentially reducing the brain’s natural cushioning system and increasing the susceptibility to impact concussion injury. Moreover, protective athletic equipment may lose its effectiveness in the extremes of heat or cold. It is unknown, however, whether the frequency of concussion is impacted by typical environmental conditions experienced during the college football season. Consequently, the aim of the present study was to observe the relationship between game time environmental conditions and the incidence of reported concussion during Football Bowl Subdivision (FBS) NCAA football games. METHODS: Reported concussions (420) during competition and game time (i.e. within 30 min of game start) temperature (T), humidity (H) and wind speed (WS) were collected from publicly available data for 3645 FBS NCAA football games for the 5 year period 2008‐2012. Indoor (dome) games (82 games, 8 concussions) and games for which hourly weather data could not be found (106 games, 8 concussions) were not included in the analysis. Environmental conditions were binned prior to frequency analysis. RESULTS: Game concussion frequency was not significantly related to T, H or WS and not related to environmental extremes (i.e. heat index or wind chill). CONCLUSION: Environmental conditions do not impact concussion frequency in college football.
Genome‐wide detection of oxidized base products in guanine quadruplex (G4) sequences by ChIP‐Seq analysis in hypoxic cells (887.1)
Authors: Pastukh Viktor , Borchert Glen , Gillespie Mark
Published: June 2021

Reactive oxygen species (ROS) generated in hypoxic signaling cause a nuclear oxidant stress accompanied by oxidative DNA modifications. Detailed studies on a few genes show that these modifications are prominent in hypoxic responsive promoters (Al‐Mehdi et al, 2012) and G4 sequences in growth regulatory genes (Clark et al., 2012). The G4 damage in hypoxia was interesting because it did not relate to the transcriptional state of the gene, was often localized close to transcription start sites, and because mutations in G4 sequences have been linked to genomic instability and carcinogenesis. To gain more insight into the impact of hypoxia‐generated ROS on genomic integrity, we used ChIP‐Seq analysis to determine if G4 sequences immunoprecipitated by an antibody to the base damage product 8‐oxoguanine were enriched on a genome‐wide scale in pulmonary artery endothelial cells cultured in hypoxia for 3h. We found two notable differences between normoxic and hypoxic cells. First, DNA contigs from hypoxic cells were ≍1/3 the size of those from normoxic cells. Second, the number of 8‐oxoG harboring G4 sequences was enriched by ≍30 fold in hypoxia compared to normoxia. These findings suggest that ROS generated during hypoxic signaling cause widespread base damage in G4 sequences and thereby point to new mechanisms of disease‐causing mutations in this enigmatic gene regulatory region.

Grant Funding Source: Supported by the NIH R01HL58234
Hypoxia reduces the function and expression of hERG potassium channels (887.2)
Authors: Lamothe Shawn , Song WonJu , Guo Jun , Zhang Shetuan
Published: June 2021

Human ether‐a‐go‐go‐related gene (hERG) encodes the pore‐forming subunit of the IKr channel which is important for cardiac repolarization. Loss of function of the hERG channel due to mutations or drugs causes long QT syndrome, a cardiac disorder with high risk of cardiac arrhythmias and sudden death. Obstructive Sleep Apnea (OSA) patients who experience intermittent hypoxia display an increased incidence of cardiac arrhythmias. We recently found that OSA patients display a trend of reduced hERG expression in atrial tissues. In the present study, we demonstrate that hypoxic culture (0.5% O2) of neonatal rat cardiomyocytes for 24 h reduced IKr by 80%. However, the same treatment did not affect the amplitudes of Na+ current, Ca2+ current, the transient outward K+ current (Ito) and the inward rectifier K+ current (IK1). Hypoxic culture (0.5% O2) decreased the abundance of hERG channels expressed in HEK 293 cells along with an enhanced expression of HIF1‐ (Hypoxia‐Inducible Factor) which is known to up‐regulate various proteins including proteolytic enzymes. Chemically inducing HIF1‐ by using cobalt chloride also decreased hERG expression. Protease inhibitors including leupeptin (100µM) completely abolished the hypoxic‐induced reduction in hERG expression. Our data raised the possibility that hypoxia decreases hERG expression by activating certain proteases, which degrade the channel protein.

Supported by the Canadian Institutes of Health Research ‐ CIHR

Grant Funding Source: supported by: CIHR
Can you believe what you see: evaluation of choline acetyl transferase (ChAT) expression in the ChAT‐eGFP transgenic mouse (89.1)
Authors: Gyengesi Erika , Münch Gerald , Paxinos George , Zaborszky Laszlo
Published: June 2021

The creation of the BAC transgenic mice expressing promoter‐specific enhanced‐ green fluorescent protein (eGFP) in the cholinergic cells provided an enormous advantage for numerous experimental methods. However, the exact distribution of the eGFP expressing, presumably cholinergic neurons in the brain was not compared with the expression of choline acetyl transferase (ChAT), the specific marker for cholinergic neurons. Here we report the comparison and discrepancies found between the distribution of ChAT‐eGFP neurons and the goat‐α‐ChAT immunoreactive neurons by using immunohistochemistry and 3D mapping with Neurolucida. We found complete overlap between the two markers in the areas of the medial septum, the ventral, horizontal and lateral nuclei of the diagonal band, the ventral pallidum, the extension of the amygdala, the globus pallidus, the caudate putamen and the striatum. Special attention was paid to areas where the expression was not overlapping, such as the cortex, the striatum, the thalamus, the hypothalamus and the mesopontine tegmentum in the brainstem. We also compared our results with those of the Allan Brain Institute maps of mRNA expression of ChAT. Weather these differences between the two technical approaches are due to the insufficient sensitivity of the antibody in areas where the level of ChAT is lower, or due to genetic default, for example gene leaking is yet to be confirmed.

Grant Funding Source: Supported by NIH grant NS023945 to LZ and Australia Fellowship awarded to GP (466028)
Morphology of Golgi stained neurons in spinal cord of African giant pouched rat (Cricetomys gambianus Waterhouse) (89.2)
Authors: Alawa Judith , Salaudeen Rukayya , Adetiba Bamidele , Alawa Clement
Published: June 2021

The spinal cord of the adult African Giant Pouched rat was studied using the rapid Golgi technique in order to get further clarification on the morphology of the neuronal cell types based on soma size, shape, dendritic density and aborization. Two main types of cells were observed to characterize the dorsal grey horn: Type 1 cells are the islet cells which were distinguished by triangulated or globular‐ shaped soma with one thick “axoniform” primary dendrite bifurcating into a Y or T secondary branches indicative of local integrating functions. They resembled the pseudounipolar cells of the dorsal root ganglion and were predominant in the cervical segments. Type 2 cells were stalked cells with several dendrites and round or polygonal soma and these were predominant in the thoracic and lumbosacral segments. The ventral grey horn demonstrated multipolar neurons with dendritic arborization arranged in a radiating or tuft‐like manner. Some cells had sparse dendrites while some other cells demonstrated unique features of a double‐pyramidal cell (conjoined neurons) joined at their apical dendrites with sparse dendritic arborization. These cells were predominant in the thoracic segment and have not been previously described. These findings give some new insight on the morphology of neurons in the spinal cord of one of the largest and unique muroids in the world.

Grant Funding Source: Supported by Grant from Ahmadu Bello University, Zaria Kaduna State. Nigeria
Hyperpolarized 13C MRS reveals hypoxia accelerates pseudo hypoxia in the diabetic kidney (890.8)
Authors: Laustsen Christoffer , Lycke Sara , Palm Fredrik , Østergaard Jakob , Bibby Bo , Nørregaard Rikke , Flyvbjerg Allan , Pedersen Michael , Ardenkjær‐Larsen Jan
Published: June 2021

In diabetic patients, reduced renal oxygen availability is associated with a higher risk of diabetic nephropathy (DN) [1]. Recently, dynamic nuclear polarization hyperpolarized [1‐13C]pyruvate has shown an increased lactate conversion (lactate dehydrogenase activity) in the diabetic kidney, as a consequence of increased nicotinamide adenine dinucleotide (NADH) substrate generated by glucose‐mediated elevated flux through the polyol pathway, while the pyruvate dehydrogenase activity (PDH) is unaltered (pseudo hypoxia) [2]. In this study, we evaluated the renal oxygenation level and energy metabolism in diabetes‐suffering rats in response to altered oxygen availability, using blood oxygen level dependent (BOLD) MRI and hyperpolarized [1‐13C]pyruvate MRI, in response to hypoxic, normoxic and hyperoxic conditions. Specifically, we investigated the enzymatic activity of lactate dehydrogenase (LDH), alanine aminotransferase (ALT) and pyruvate dehydrogenase (PDH). We show that reduced oxygen availability in the diabetic kidney alters the energy metabolism of pyruvate by increasing the lactate and alanine formation from pyruvate despite intact oxidative phosphorylation.

Grant Funding Source: Supported by The Simon Spies Foundation, The Danish Kidney Foundation, Helen and Ejnar Bjørnows Foun
Deficiency in NBCe2 causes distal renal tubular acidosis (891.2)
Authors: Wen Donghai , Cornelius Ryan , Warner Paige , Boettger Thomas , Sansom Steven
Published: June 2021

The pathogenesis of distal renal tubular acidosis (dRTA) is not fully understood. Here we show that the electrogenic Na/HCO3 cotransporter NBCe2 is involved in the pathophysiology of dRTA by reabsorbing HCO3 in the collecting duct (CD). NBCe2 knockout (KO) and wild type (WT) mice were fed with acid water for 7‐10 days and placed in metabolic cages. Immunohistochemistry (IHC) and Western blot were used to examine the expressions of NBCe2 and H‐ATPase B1 in the kidneys. IHC showed NBCe2 was expressed mostly at the apical membrane of Type A intercalated cells (α‐IC) of the CD. The H‐ATPase B1 expression was higher in the plasma membrane of α‐IC in NBCe2 KO than WT, suggesting compensation for NBCe2 defect. As compared with WT, NBCe2‐KO exhibited significantly lower plasma pH, [HCO3] and [K], while the urine pH, K clearance and transtubular K gradient were increased. NBCe2 expression was also examined in cultured MDCK‐C11 cells by immunocytochemistry (ICC), which showed that NBCe2 was expressed selectively at the apical membrane in C11 cells. The intracellular pH (pHi) recovery rate in C11 cells was recorded using BCECF. Knocking down of NBCe2 expression by siRNA significantly decreased the pHi recovery rate in C11 cells. In conclusion, NBCe2 plays an important role in reabsorbing HCO3 in the CD. NBCe2 deficiency leads to hypokalemic acidosis and is another form of dRTA.

Grant Funding Source: NIDDK
Protein phosphatase 1 Inhibitor‐1 deficiency causes hypotension and reduces the phosphorylation of renal NaCl cotransporter (892.18)
Authors: Picard Nicolas , Trompf Katja , Yang Chao‐Ling , Miller R. , Carrel Monique , Loffing‐Cueni Dominique , Fenton Robert , Ellison David , Loffing Johannes
Published: June 2021

The thiazide‐sensitive NaCl cotransporter (NCC) of the renal distal convoluted tubule (DCT) controls ion homeostasis and blood pressure (BP). Gain‐of‐function in NCC‐regulating kinases or loss‐of‐function of NCC alters BP. The size and location of the DCT has hindered efforts to identify new molecular regulators of this protein. Here, we performed automated sorting of mouse DCTs and microarray analysis for identification of DCT‐enriched gene products, which may regulate NCC. We identified protein phosphatase‐1 inhibitor‐1 (I‐1) as a DCT enriched transcript. Immunolocalisation revealed I‐1 expression in mouse and human DCTs and thick ascending limbs. Coexpression of NCC with I‐1 increased thiazide‐ dependent Na+ uptake, whereas RNAi‐mediated knockdown of I‐1 reduced NCC phosphorylation. Likewise, levels of phosphorylated NCC decreased by approximately 50% in I‐1 knockout mice (I1‐/‐). Compared with WT mice, I1‐/‐ mice had lower arterial BP, but did not display other metabolic features of NCC dysregulation. Thus, I‐1 is a DCT enriched gene product that controls arterial BP, possibly through regulation of NCC.

Grant Funding Source: Swiss National Fund