bluuebunny/crossref_metadata_2025 huggingface dataset:
Role for Kv1.3 channels in sympathetic neurovascular transmission
Authors: Damon Deborah H. , Bagher Pooneh , Morielli Anthony D , Segal Steven S
Published: June 2021

We tested the hypothesis that Kv1.3 channels affect sympathetic neurovascular transmission using margatoxin (MgTX), a specific inhibitor. In isolated rat tail arteries during electrical field stimulation (4 Hz, 60 volts, 1 min) MgTX (10 nM) decreased release of 3H‐norepinephrine (NE) from 5.3+1.1% to 2.7+0.4% (p<0.05, n=6). In superfused cremaster preparations of anesthetized mice, local periarteriolar nerve stimulation (PNS) with a glass microelectrode (2 µm tip) produced constriction (57+3% at 4 Hz, 75+4% at 8 Hz; resting diameter, 43+3 µm) which MgTX perifusion (100 nM, 50 µm pipette tip) reduced (to 37+2 % at 4 Hz and 47+5% at 8 Hz; p<0.05, n=6). Phentolamine (1 µM) inhibited constriction to PNS (n=3) while MgTX had no effect on constriction to 10 nM NE (47+10%; n=3). These findings suggest that MgTX inhibits Kv1.3 channels in perivascular sympathetic nerve terminals. MgTX perifusion also reduced arteriolar diameter (by 16+6%, n = 6; p<0.05 vs. vehicle, n=3). These data indicate that the activation of Kv1.3 channels in perivascular sympathetic nerve terminals enhances neurovascular transmission and suggest that inhibiting Kv1.3 channels in vascular cells increases vasomotor tone. Support: NIH HL076774, NS050623, HL056786, HL086483, AR048523.
Effects of reducing blood lipids on endothelial function in severe atherosclerosis
Authors: Miller Jordan D , Castaneda Lauren E , Ryan Samantha N , Serrano Kristine M , Brooks Robert M , Young Stephen G , Heistad Donald D
Published: June 2021

Endothelial function is impaired by atherosclerosis and can be improved by lowering plasma lipid levels. In this study, we tested the hypothesis that endothelial function could be improved by lowering plasma lipid levels in mice with severe atherosclerotic lesions. We took advantage of a severely hypercholesterolemic mouse model (Ldlr−/−Apob100/100Mttpfl/flMx1Cre+/+) in which the hypercholesterolemia can be "switched off" by induction of the Cre transgene. After 12 months of hypercholesterolemia, endothelial function was impaired [maximum relaxation (MR) to acetylcholine, 43 ± 5% vs. 71 ± 5% in normolipidemic control mice]. At 14 months (i.e., after 2 additional months of hypercholesterolemia), MR to acetylcholine was even more impaired (MR of 10 ± 6% vs. 76 ± 5% in normolipidemic control mice). Sensitivity to nitric oxide was also impaired by long‐term hypercholesterolemia (MR to nitroprusside after 12 and 14 months of hypercholesterolemia was 75 ± 5% and 47 ± 10%, respectively, vs. 90 ± 1% in normolipidemic control mice). In an additional group of mice, the Cre transgene was induced at 12 months of age, thereby switching off hypercholesterolemia, and endothelial function was evaluated at 14 months of age. In these mice, the MR to acetylcholine was 55 ± 8% and the MR to nitroprusside was 87 ± 1%. Thus, eliminating hypercholesterolemia eliminated the decline in endothelial function that would normally occur between 12 and 14 months of age. Our data suggest that aggressive, short‐term lipid lowering improves vascular NO sensitivity and prevents a precipitous decline in endothelial function in severe atherosclerosis in mice.
Low salt diet intensifies conducted vasoconstriction via an angiotensin II receptor mediated mechanism
Authors: Riemann Mads , Ngo Anh Thuc , Holstein‐Rathlou Niels‐Henrik , Torp‐Pedersen Christian
Published: June 2021

Objective

Our aim was to investigate 1) the effect of diet sodium content on the potency of conducted vasoconstriction in mouse striated muscle arterioles in vivo, and 2) whether angiotensin II mediates these effects.

Methods

KCl was applied locally to induce conducted vasoconstriction in second order arterioles (diameter 36.5±1.6 μm) in the cremaster muscle in anesthetized male C57 mice (n=38). Vasoconstriction was measured locally and upstream from the application site (500 and 1000 μm), using video microscopy. Stimulation was adjusted to 50 % local vasoconstriction in all animals.

Results

Animals on low sodium diet (0.015%) for 2‐3 weeks exhibited a stronger conduction of vasoconstriction compared to animals on high sodium diet (3%). At 500 μm, the vessel diameter in the low salt group was 47±2.8% of resting diameter and 90±2.1% in the high salt group p<0.01. At 1000 μm, vessel diameter in the low salt group was 63±5.8% versus 95±1.3% in the high salt group p<0.01. These differences were attenuated by the AT1 blocker losartan. Similar but less pronounced results were seen after 6 months on high or low salt diet.

Conclusion

Our results indicate that conducted vasoconstriction to KCl in mouse cremaster arterioles is intensified by low salt diet, and that this effect is modulated by angiotensin II via AT1 receptors. This phenomenon is seen both after short (2 weeks) and long term (6 months) exposure to the low salt diet.
Rescue of cardiac leptin receptor improves diastolic function and prevents cardiac lipid accumulation in db/db mice
Authors: Maready Matthew W , Hall Michael E , Murakami Takashi , Stec David E
Published: June 2021

One mechanism by which obesity is thought to lead to heart disease is by increasing lipid accumulation in the heart, a process known as cardiac lipotoxicity. One adaptive mechanism to combat lipotoxicity is to increase the levels of leptin which stimulates β‐oxidation and shunts fatty acids from away from storage reducing lipid accumulation. In order to determine if leptin can prevent cardiac lipotoxicity, we generated a novel mouse model in which the cardiac leptin receptor was rescued in db/db mice. We generated a transgenic mouse model in which leptin was specifically overexpressed in the heart and crossed these onto the db/db background to obtain db/db‐rescue mice. db/db mice exhibited a significantly lower E/A ratio which is a measure of early to late diastolic filling as compared to lean or rescue mice averaging 1.5 + 0.07 in db/db vs. 1.9 + 0.08 and 1.8 + 0.11 in lean and rescue mice. No differences in systolic function were observed between db/db and lean mice. db/db and rescue mice exhibited similar significant increases in plasma leptin, triglycerides, and glucose as well as in body weight as compared to lean mice. Cardiac triglyceride levels were significantly increase in db/db as compared to lean and rescue mice and averaged 13.4 + 4.2 vs. 3.8 + 1.6 vs. 3.8 + 0.7 mg/g. These results show that despite significant obesity and increases in plasma glucose and triglycerides, rescue mice are protected against lipid accumulation by a direct effect of leptin on cardiac tissue. This work was supported by NIH grant HL‐51971 and a grant from the American Heart Association.
Myostatin inhibition enhances the effects of exercise on performance and metabolic outcomes in aged mice
Authors: LeBrasseur Nathan K , Schelhorn Teresa , Bernardo Barbara , Loria Paula , Brown Thomas A
Published: June 2021

The objective of this study was to investigate the effects of 4 weeks of exercise training (Ex), myostatin inhibition (MyoI) and Ex+MyoI on performance and metabolic outcomes in 24‐month old mice. At study termination no differences were noted in body weight or composition by computed tomography, however, the mean weight of quadriceps muscles were 17% greater in MyoI mice relative to vehicle (Veh) (p < 0.01). In performance measures, Ex+MyoI mice demonstrated a > 2‐fold increase in treadmill running time and distance compared to Veh (both p < 0.001) and both Ex and Ex+MyoI groups demonstrated increased habitual activity compared to Veh (p < 0.05). No differences were observed in grip strength or nerve‐evoked peak tetanic force; however, all treatment groups demonstrated >30% reductions in muscle fatigue relative to Veh in elicited contractions (all p < 0.01). In metabolic measures no differences were observed in glucose tolerance but Ex and Ex+MyoI demonstrated significantly greater reductions in basal glucose in response to an insulin bolus compared to Veh. Increased oxygen consumption and basal metabolic rate were also demonstrated by MyoI and Ex+MyoI mice relative to Veh (all p < 0.05). These data suggest that combining exercise training with a pharmacological strategy to increase muscle mass may confer significant improvements upon both physical function and whole body metabolism in older individuals.
Physical Activity Reduces Prostate Carcinogenesis in a Transgenic Model
Authors: Esser Karyn , Harpole Clifford , Prins Gail , Diamond Alan
Published: June 2021

Several epidemiological studies have reported an inverse association between physical activity and the risk of prostate cancer. In general, as exercise intensity increased in the rats/mice, the likelihood that physical activity inhibited carcinogenesis increased. In order to establish an animal model to investigate the effects of physical activity on prostate cancer development, the present study used C3(1)Tag mice that are predisposed to prostate cancer due to the directed expression of SV40 oncogenes combined with voluntary wheel running exercise. The results presented indicate that prostatic cancer progression is likely delayed or diminished by wheel running in a dose dependent manner. Mice that ran > 5Km/group exhibited 83% of the dorsolateral prostates as within normal levels for pathology vs. 43% for the < 5 km/day group (p=0.16). In addition, the pathologic progression to high‐grade PIN and local invasion, considered to be an early event in the formation of prostate adenocarcinoma, was significantly reduced with increased running. Forty three percent of dorsolateral prostates from mice that ran less than 5 km/day were classified with advanced pathology as compared to none in mice that ran more than 5.0 km/day (p=0.05). These findings provide further evidence that exercise acts to decrease the progression of prostate cancer and they establish a transgenic animal model for future mechanistic studies.
Effects of Maternal Exercise on Fetal Breathing and Hiccups
Authors: Million Stephanie , Gustafson Kathleen M , May Linda E.
Published: June 2021

The hypotheses that fetal breathing and hiccups alters fetal heart rate and that exercise exposed fetuses have increased breathing activity compared to non‐exercise exposed fetuses were tested utilizing a biomagnetometer at various gestational ages. Mothers were classified as exercisers if they performed moderate intensity aerobic exercise at least 30 minutes 3 times per week. Mothers in the control category did not partake of a regular exercise regime. We analyzed fetal breathing movements and hiccups waveforms for frequency, duration, and cycles per episode; heart rate minimum, maximum, and mean; sympathetic and vagal tone, and fetal activity state. Average heart rate during breathing movements relative to non‐breathing periods was similar. Breathing frequency increases at 32 weeks GA. Exercise exposed fetuses show an increased frequency in breathing compared to controls. Exercise exposed females have the greatest increase in frequency relative to exercise exposed males, or control males and females. Fetal heart rate decreases during episodes of hiccups which corresponded with decreased sympathetic tone and increased vagal tone. These findings suggest a potential benefit of maternal exercise on fetal diaphragm development. These data suggest a potentially positive prenatal programming effect which may prove to be the earliest intervention to prevent SIDS.
Hypogonadal Male Runners Do Not Display Endocrine or Performance Decrements during Prolonged Endurance Exercise
Authors: Hew‐Butler Tamara Dawn , Jordaan Esme , Noakes Timothy D , Soldin Steven J , Verbalis Joseph G
Published: June 2021

Study aims

1) determine if hypogonadal male runners exhibit an impaired performance or endocrine response 2) determine which endocrine factors influence testosterone in male runners

Design

58 males participating in ultramarathon plus 2 lab trials with 10 subjects

Results

The only statistically significant difference in any measured parameter between eugonadal versus hypogonadal men was [androstenedione]p Δ(61.9 vs. 98.9 ng/dl). Statistically significant linear correlations noted between [testosterone]p Δversus: [NT‐proBNP]p Δ(r = 0.41) and [AVP]p Δ(r = ‐0.38). Significant positive correlations noted between age versus: [testosterone]p Δ(r = 0.41) and finish time (r = 0.31) but not pre‐race [testosterone]p . [NTproBNP]pΔ, age, [AVP]pΔ, [cortisol]pΔ, urine osmolality Δand pre‐race [testosterone]p accounted for 68% of the variance noted in post‐race [testosterone]p in nonrecursive pathway diagrams.

Conclusions

Low testosterone levels in male marathoners were not associated with decrements in performance or endocrine‐stress response. Collective clusters of endocrine and/or non‐endocrine factors ‐ such as age, BNP, AVP and cortisol ‐ perhaps should be assessed in tandem when considering therapeutic options aimed at male hypogonadism.

Research support

Astellas Pharma US, Inc., Deerfield, IL and by Grant M01RR‐023942‐01 from the National Center for Research Resources (NCRR)
Habitual aerobic exercise is associated with reduced vascular endothelial cell oxidative stress, NADPH oxidase and NFκB in middle‐aged and older humans
Authors: Pierce Gary L. , Donato Anthony J. , Silver Annemarie E. , Chiang Rhea , Seals Douglas R.
Published: June 2021

Middle‐aged and older (MA/O) adults who perform habitual aerobic exercise demonstrate enhanced vascular endothelial function compared with their sedentary peers, but the molecular mechanisms involved are unknown. Brachial artery flow‐mediated dilation, a measure of endothelium‐dependent dilation, was 34% higher (6.8 ± 0.9 vs. 5.1 ± 0.4 %δ, P<0.05) in regularly exercising (EX, n=12, 62 ± 2 yrs, 8M/4F) vs. sedentary (SED; n=25, age 62 ± 1 yrs, 12M/13F) healthy MA/O adults, whereas endothelium‐independent dilation to sublingual nitroglycerin was not different (29.3 ± 1.8 vs. 26.7 ± 1.4 %δ, P=0.29). In endothelial cells obtained from the brachial artery, expression of nitrotyrosine (NT), a cellular marker of oxidative stress (0.48 ± 0.07 vs. 0.74 ± 0.10 immunofluorescent intensity/HUVEC intensity), NADPH oxidase p47phox, a subunit of the oxidant enzyme NADPH oxidase (0.41 ± 0.04 vs. 0.76 ± 0.09), and nuclear factor κB (NFκB), a redox‐sensitive proinflammatory transcription factor (0.39 ± 0.04 vs. 0.64 ± 0.06), were 35‐50% lower in EX, whereas manganese superoxide dismutase (MnSOD), a mitochondrial antioxidant enzyme, was 74% higher (0.48 ± 0.07 vs. 0.28 ± 0.04) (all P<0.05 vs. SED). NT was positively related to NADPH oxidase p47phox (r=0.64, P<0.01) and NFκB (r=0.29, P=0.05), but not to MnSOD. Compared with their sedentary peers, habitually exercising MA/O adults have reduced vascular endothelial cell oxidative stress related to decreased NADPH oxidase and NFκB. Supported by NIH AG000279, AG013038, AG022241, AG006537, and RR00051.
Associations between HIF1A gene sequence variation and cardiorespiratory fitness: The CARDIA Fitness Study
Authors: Sarzynski Mark A. , Rankinen Tuomo , Sternfeld Barbara , Fornage Myriam , Sidney Steve , Bouchard Claude
Published: June 2021

Hypoxia inducible factor 1 alpha (HIF1A) is a transcription factor that regulates expression of several genes in response to hypoxia. Sequence variation in the HIF1A gene (rs11549465) has previously been associated with VO2max training response and elite endurance athlete status in Caucasians. Purpose of our study was to examine the association of DNA sequence variants in the HIF1A gene locus and cardiorespiratory (CR) fitness level measured at baseline of the CARDIA Fitness Study. The study population consisted of 4258 (2129 African‐Americans, 2162 Caucasians) young adults with mean age of 24.9 (SD 3.6) years. CR fitness was measured as treadmill time (TMT) on a graded exercise test. The associations between TMT and HIF1A SNPs (13 for African‐Americans, 6 for Caucasians; minor allele frequency > 4%) were analyzed using general linear models with adjustments for age, sex, and body weight. In Caucasians, SNP rs1957757 was significantly associated with TMT (nominal p=0.001, Bonferroni‐corrected p=0.006): the T/T homozygotes (n=21) had 1.3 and 1.5 minutes longer TMT than the C/T heterozygotes (n=316) and the C/C homozygotes (n=1624), respectively. No other SNP was significantly associated with TMT in Caucasians. None of the SNPs were associated with TMT in African‐Americans. Our data suggests that DNA sequence variation in the HIF1A gene locus is associated with treadmill time in Caucasian young adults.
A genetic disease in humans demonstrates the importance of hypoxia‐inducible factor in skeletal muscle metabolism
Authors: Formenti Federico , Clarke Kieran , Dorrington Keith L , Edwards Lindsay , Emmanuel Yaso , Lappin Terence RJ , McMullin Mary F , McNamara Christopher J , Mills Wendy , Murphy John A , O'Connor David F , Percy Melanie J , Smith Thomas G , Treacy Marilyn , Robbins Peter A
Published: June 2021

The transcription factor, hypoxia‐inducible factor (HIF) regulates the expression of a number of metabolic genes. In the recessive condition of Chuvash Polycythemia (CP), the normal degradation of HIF in euoxia is slowed by functional mutation within the von Hippel‐Lindau (VHL) gene. Thus the disease of CP provides an opportunity to understand the role of the HIF‐VHL pathway in metabolic regulation at a systemic level. We recruited 5 CP patients and 5 controls, matched for gender, and similar for age, height and weight (CP vs control: 28±8 vs 32±12 yrs; 1.67±0.1 vs 1.74±0.1 m; 61±6 vs 72±6 kg; mean±s.d.). We measured work rate and lactate during an exercise capacity test on a cycle ergometer, and skeletal muscle magnetic resonance spectroscopy at rest and during light exercise (3, 4 & 5 Watt). Compared with controls, CP patients showed a limited exercise capacity (CP vs control: 2.4±0.9 vs 3.4±0.8 W/kg; p < 0.05), early lactate accumulation, greater phosphocreatine (PCr) depletion (Fig.1) and a greater fall in pH during exercise. We conclude that the VHL‐HIF pathway significantly affects metabolic regulation at a systemic level.

Figure 1
Effects of acute severe exercise on insulin‐ and insulin‐like growth factor‐1‐mediated vasorelaxation in spontaneously hypertensive rats
Authors: Li Ren‐Ting , Su Chia‐Ting , Yang Ai‐Lun
Published: June 2021

Exercise enhances the vascular function mainly by improving endothelial function. The way of exercise influences on hypertension‐induced vascular dysfunction remains unclear. Thus, the aim of this study was to examine the effects of acute severe exercise on insulin‐ and insulin‐like growth factor‐1 (IGF‐1)‐mediated vasorelaxation in spontaneously hypertensive rats (SHR). Three groups of rats were used in this study: SHR with exercise, SHR, and Wistar‐Kyoto rats (WKY) as control. The SHR with acute severe exercise group ran on treadmill at the speed of 28‐30 m/min until exhausted. Thoracic aortas were isolated to analyze vascular responses in organ baths. Selective inhibitors were used to examine the roles of endothelial nitric oxide synthase (eNOS) and phosphatidylinositol‐3 kinase (PI3K) in the vasorelaxation. Furthermore, the vascular response induced by sodium nitroprusside (SNP, a NO donor) was examined. Our results showed that, 1) insulin‐ and IGF‐1‐mediated vasorelaxation was significantly lower in SHR than WKY; 2) acute exercise ameliorated these adverse effects in SHR; 3) after treating either wortmannin (a PI3K inhibitor) or L‐NAME (a eNOS inhibitor), the differences of vascular responses among three groups were eliminated; 4) no significant differences of the SNP‐induced vasorelaxation were found among three groups. Our findings suggested that acute severe exercise could reverse the impairments of vascular function in hypertension.
High sucrose diet impact on voluntary wheel running prevents obesity in rats
Authors: Scarpace Erin T , Tumer Nihal
Published: June 2021

Two important factors contributing to energy balance are caloric intake and physical activity. One form of volitional activity is voluntary wheel running (WR). The extent of WR diminishes with age and obesity. We examined the impact of a high fat (HF) (60% kcal, fat; 7% kcal, sucrose, 5.24 kcal/g) and a high sucrose (11% fat; 60% sucrose, 4.07kcal/g) diet on WR over 12 weeks compared with a chow diet (4% fat; 7% sucrose, 3.41kcal/g). The HF fed rats ate the most calories during the first week, with the high‐sucrose fed consuming more than controls, but less than HF fed rats. All rats consumed similar amounts of calories for the remaining 11 weeks, and overall cumulative caloric consumption was unchanged across groups. Only the HF fed rats became progressively obese. The rats in all groups ran progressively less over the 12 weeks with a 36% decrease in chow (p<0.012), a 37% decrease in the HF (p<0.032), and a 12.9% decrease in the high sucrose (p<0.018). Those on the high‐sucrose diet had the smallest decrease in running (p<0.035). In summary, voluntary WR declined progressively over 12 weeks on all diets, but decrease was least in the rats consuming the high‐sucrose diet. This higher level of physical activity may explain why these rats did not become obese, compared with the HF fed, despite consuming a similar amount of calories. Supported by Medical Research Service, Dept of Veterans Affairs and NIH AG026159.
The role of central ROS and NO in aldosterone (ALDO)/salt‐induced hypertension
Authors: Xue Baojian , Badaue‐Passos Daniel , Beltz Terry G. , Bhalla Ramesh C. , Hay Meredith , Johnson Alan Kim
Published: June 2021

It has been shown that increased reactive oxygen species (ROS) production in kidneys and blood vessels contributes to elevated blood pressure (BP) in rats with mineralocorticoid excess. Nitric oxide (NO) also plays an important role in the regulation of ROS production and BP. However, the role of ROS and NO in the brain in the pathophysiology of mineralocorticoid excess is not fully understood. In the present study, we tested the hypothesis that central ROS and NO production is involved in the BP increase produced by ALDO/salt treatment. BP was measured in male and female rats with the use of telemetry implants. Rats were infused with ALDO (0.75 μg/h, 28 days) via an osmotic pump implanted subcutaneously and given access to 1% NaCl as the sole drinking fluid. ICV, but not subcutaneous, infusions of apocynin (4 μg/kg/min) for 28 days attenuated ALDO/salt‐induced hypertension in male rats (central n=3, Δ16.5± 2.3 vs peripheral n=2, Δ30.4 ± 4.1 mmHg). In a parallel study, ICV L‐NAME infusion (50 μg/kg/day) enhanced the pressor effects in ALDO/salt‐treated female rats (n=3, Δ21.7±1.1 mmHg) when compared to ALDO/salt‐treated females with peripheral L‐NAME (n=2, Δ10.6±1.2 mmHg). Central infusions of apocynin alone or of L‐NAME alone had no effect on BP. These results suggest that increased ROS and/or decreased NO in the central nervous system play an important role in the development of ALDO/salt‐induced hypertension.

(Support: NIH HL‐59676, HL‐62261, HL‐14388, & DK‐66086)
Electrical stimulation of the aortic depressor nerve in conscious rats still causes a hypotensive effect after blockade of the autonomic nervous system and nitric oxide production
Authors: Durand Marina de Toledo , Castania Jaci Airton , Salgado Maria Cristina Oliveira , Salgado Helio Cesar
Published: June 2021

Previous observations indicated that α1 ‐ adrenergic receptor blockade did not blunt, completely, the hypotensive response to electrical stimulation of the aortic depressor nerve (ADN) in conscious normotensive and L‐NAME hypertensive rats. In the present study it was examined whether the reflex bradycardia played a role in the above hypotensive response. Rats received catheters into the femoral artery and vein and a pair of electrodes around the ADN under pentobarbital anesthesia. ADN stimulation (1mA, 2 ms, 5 to 90 Hz) was applied during 20s, before and after triple pharmacological blockade (prazosin + atropine + atenolol). The hypotensive response to ADN stimulation was greater in L‐NAME hypertensive (‐26±4 to ‐70±10 mmHg; N=6) as compared to normotensive (‐21±3 to ‐54±2 mmHg; N=8) rats, while the bradycardic responses were similar (‐40±12 to ‐147±39 bpm and ‐17±3 to ‐94±19 bpm). After the triple pharmacological blockade the bradycardic response was abolished. Nevertheless, the hypotensive response was not completely blunted and the significant remnant fall in mean arterial pressure was similar in normotensive (12±2 to 27±2 mmHg) and L‐NAME hypertensive rats (13±2 to 27±3 mmHg). These results show that the bradycardic response did not affect the residual fall in pressure induced by ADN stimulation and suggest the activation of a non‐adrenergic vasodilatory mechanism which does not involve nitric oxide.
Adenovirus‐mediated gene transfer of Mn superoxide dismutase to carotid body normalizes enhanced chemoreceptor function in heart failure rabbits
Authors: Ding Yanfeng , Li Yu‐Long , Yin Jingxiang , Zimmerman Matthew C , Schultz Harold C
Published: June 2021

Peripheral chemoreflex sensitivity is enhanced in both clinical and experimental chronic heart failure (CHF). We have found CuZn superoxide dismutase (SOD) gene transfer to the carotid body (CB) and tempol (an SOD mimetic) reverse the enhanced chemoreceptor function in heart failure rabbits. Here we investigated the role of MnSOD in the enhanced chemoreceptor activity and function of the CB in CHF rabbits. MnSOD protein expression was lower in CHF CB compared with that in sham CBs. Ad MnSOD (1x108 pfu/ml) gene transfer to the CBs significantly increased MnSOD expression in CHF CBs and reduced the baseline renal sympathetic nerve activity (RSNA) and the response of RSNA to hypoxia in the CHF rabbits. Ad MnSOD decreased the baseline single‐fiber discharge from CB chemoreceptors (6.4± 1.3 vs.10.5±0.9 imp/s at ~100 mm Hg PO2) and the response to hypoxia (18.4±2.1 vs. 36.7±2.2 imp/s at ~40 mm Hg PO2, p<0.05) in CHF rabbits. In addition, Ad MnSOD normalized the blunted IK in CB glomus cells from CHF rabbits (362±41 vs. 520±65 pA/pF at +70 mV, p<0.05). Ad MnSOD also normalized the blunted IK induced by angiotensin II in CB glomus cells from sham rabbits. These results suggest that decreased MnSOD in the CB may contribute to the enhanced CB chemoreceptors activity and peripheral chemoreflex function in CHF rabbits.

Supported by NIH grant PO‐1 HL 62222
DECREASED SMALL CONDUCTANCE, CALCIUM‐ACTIVATED POTASSIUM (SK) CURRENT UNDERLIES INCREASED EXCITABILITY OF PVN‐RVLM NEURONS AND SYMPATHOEXCITATION IN ANG II‐SALT HYPERTENSIVE (HT) RATS
Authors: Chen Qing‐Hui , Dong Ying , Cardoso Leonardo , Pedrino Gustavo R. , Shi Peng , Toney Glenn M.
Published: June 2021

A neural mechanism responsible for sympathoexcitation in HT rats was investigated. We hypothesized that reduced SK current in PVN neurons projecting to RVLM (PVN‐RVLM) could contribute to increased excitability and sympathetic outflow in HT rats. In voltage‐clamp recordings, the amplitude of SK current in neurons from HT rats (12±6 pA, n=5) was significantly (p<0.01) less than that from neurons of normotensive (NT) rats (73±12 pA, n=5). In current‐clamp recordings, graded current injections evoked graded increases in discharge frequency. Maximum discharge was evoked by +200 pA injections in neurons from HT rats (47±5 Hz, n=10). This response was significantly greater (P<0.001) than that of neurons from NT rats (25±2 Hz, n=10). The SK channel blocker UCL1684 (100 nM) significantly increased (p<0.05) discharge in neurons from NT rats (39±4 Hz, n=6), but had no effect on neurons from HT rats (46±2 Hz, n=10). The contribution of SK channel activity in regulating ongoing sympathetic activity was assessed by microinjecting UCL1684 into the PVN of anesthetized rat. UCL1684 significantly (P<0.05) increased RSNA by 58±14 % and MAP by 10±1 mmHg in NT rats (n=4), but was without effect in HT rats (n=4). We conclude that increased excitability of PVN‐RVLM neurons may contribute to sympathoexcitation and maintenance of hypertension. Reduced SK current in these neurons may constitute an underlying neural mechanism. Support: AHA0865107F (QHC) & HL076312 (GMT)
Rostroventrolateral medullary neurons that modulate glycemia
Authors: Verberne Anthony Johannes , Sartor Daniela M
Published: June 2021

The sympathetic nervous system alters glycemia via mechanisms that include the release of adrenaline. We tested the hypothesis that neuroglucoprivation activates a sub‐population of medullospinal neurons in the rostroventrolateral medulla (RVLM) and that the RVLM influences blood glucose levels. In isoflurane‐anesthetized, paralysed male Sprague‐Dawley rats, we recorded the discharges of RVLM spinally‐projecting neurons along with arterial blood pressure (AP) and heart rate. Neurons were tested for sensitivity to (i) baroreceptor stimulation, (ii) cholecystokinin (CCK, 4 μg/kg, i.v.), (iii) phenylbiguanide (PBG, 10 μg/kg, i.v.) and (iv) neuroglucoprivation (2‐deoxyglucose, 2‐DG; 300 mg/kg, i.v.). RVLM neurons (n=20) were barosensitive (17/20), PBG sensitive and some were sensitive to CCK. Some (8/16) were modestly inhibited by 2‐DG. We also characterised a small population of neurons (n=3) that were prominently activated by 2‐DG. These had slow conducting spinal axons and were insensitive to baroreceptor activation. In separate experiments under urethane anaesthesia (1.4 g/kg, i.v.), bicuculline (100 pmol/100 nl) was microinjected bilaterally into the RVLM. Disinhibition of the RVLM increased AP and blood glucose concentration rose from 4.7±0.4 mM to 15.1±1.0 mM (P<0.05; n=4). Neurons activated by 2‐DG are probably those that control adrenaline release and produce hyperglycemia.
Cardiovascular responses during static exercise after blockade of angiotensin receptor‐AT2 subtype within the rostral and caudal ventrolateral medulla
Authors: Tedesco Anthony , Ally Ahmmed
Published: June 2021

Angiotensin receptors (AR), classified into AR‐AT1 and AR‐AT2 subtypes, are located in different regions of the central nervous system, particularly within the cardiovascular control centers in the brainstem. We previously reported the role of AR‐AT1 receptors within the medulla on cardiovascular responses during the exercise pressor reflex (Neuroscience Research, 60(3): 340‐348, 2008). In this study, we investigated the role of angiotensin receptor‐AT2 subtype (AR‐AT2) within the rostral (RVLM) and caudal (CVLM) ventrolateral medulla in modulating increased cardiovascular responses during static muscle contraction using anesthetized rats. Bilateral microdialysis of a selective AR‐AT2 antagonist, PD123319 (10 µM), for 30 minutes into the RVLM augmented increases in mean arterial pressure (MAP) and heart rate (HR) during a static muscle contraction. After 60 minutes of discontinuation of the drug, MAP and HR values in response to a muscle contraction returned to baseline levels. In contrast, bilateral microdialysis of PD123319 (10 µM), into the CVLM attenuated cardiovascular responses during a static muscle contraction and the responses recovered after 60 minutes of discontinuation of the drug. These results demonstrate that medullary AR‐AT2 plays an important role in modulating cardiovascular function during the exercise pressor reflex.
“Targeting host signaling pathways for inhibiting HIV replication”
Authors: August Avery
Published: June 2021

HIV‐1 utilizes host cell pathways to replication and generate new virus and productive infection of T cells requires T cell activation and actin cytoskeletal reorganization. We have explored the cellular signaling pathways used by this virus with the goal of targeting them to inhibiting viral replication. We show that HIV‐1 utilizes the T cell receptor (TCR) and CD28 costimulatory pathways to enhance viral transcription. TCR/CD28 activation of T cells results in enhanced activation of HIV‐1 proviral transcription via tyrosine phosphorylation of the GEF Vav and activation and binding of NF‐¿B to the HIV‐ 1 long terminal repeat. We also show that the tyrosine kinase ITK is activated by the TCR/CD28 signaling pathway, as well as the viral co‐receptor CXCR4. ITK modulates the Vav signaling pathway and regulates TCR and CXCR4 induced cytoskeletal rearrangements. We show that targeting ITK via siRNA, an ITK selective inhibitor, or using a dominant negative ITK leads to reduction in p24 levels after HIV‐1 infection. Targeting ITK after HIV‐1 infection has been established leads to a decrease in virus replication and spread. This was due to a block in several steps in the viral life cycle, viral entry due to reduced actin rearrangement, and blocks in viral transcription and viral particle formation. Our data suggest that targeting host signaling machinery may be an effective approach to targeting HIV‐1, reducing the options for the escape of viral mutants.
Anatomic changes in the facial nucleus (FN) and surrounding area of goats after near total chronic destruction of the pre‐Botzinger complex (PBC) area
Authors: Neumueller Suzanne , Krause Katie , Bonis Josh , Qian Baogang , Pan Lawrence , Forster Hubert
Published: June 2021

We have reported normal breathing and arterial blood gases in awake and sleeping goats after step‐wise destruction of 80 to 92% of the PBC and surrounding area (FASEB J. 2008 22:755.16). To explore possible anatomic sites of plasticity following this destruction, the cryopreserved medulla of 4 PBC lesioned goats and 4 control goats were cyrosectioned (25ìm), Nissl stained, and then we quantified the area and number of neurons 2mm caudal and rostral to the caudal boundary of the FN and the area ventral and lateral to this 4mm area. The area (mm2) of the first 2mm of the FN was nearly 75% less (P<0.001) in PBC lesioned goats than in control goats. As a result, the total number of FN neurons was about 60% less (P<0.001) in lesioned than in control goats. The number of neurons for 1mm caudal to the FN did not differ between lesioned and control goats. Ventral to the FN and ventral to the 2mm caudal to the FN, there was no difference in the total area (P=0.291) between lesioned and control goats but throughout this area there were about 50% more (P<0.001) neurons in the lesioned than in control goats. Lateral to the FN and lateral to the 2mm caudal to the FN, there was no difference (P=0.405) in numbers of neurons between control and lesioned goats. We conclude that chronic lesions of the PBC result in anatomic change in the FN and areas caudal and ventral to the FN. Supported by NIH 25739 and the Department of Veterans Affairs.
Effect of neuronal nitric oxide synthase inhibition on ischemia‐induced gasping in arterially‐perfused adult rat
Authors: Chang Johnathan , Solomon Irene C
Published: June 2021

Previous in vivo studies in the developing (2‐15 day old) rat have demonstrated that anoxia‐induced gasping is modulated by nitric oxide (NO), such that blockade of nitric oxide synthase (NOS) delays the gasping onset, prolongs gasping duration, and reduces gasp frequency. The role of NO in the anoxic/ischemic ventilatory response in a more mature rat preparation, however, requires clarification. Therefore, we examined the ischemia‐induced gasping response in 9 arterially‐perfused adult rat preparations during either perfusion with the neuronal NOS inhibitor 7‐nitroindazole (7‐NI; 5 µM, n=4), vehicle (DMSO/aCSF; n=1), or normal aCSF (n=4). We found that although perfusion with 7‐NI was ineffective in altering the frequency, amplitude, or patterning of basal phrenic bursts, it modified the timing and patterning of ischemia‐induced gasps. Under these conditions, the duration between gasps was prolonged and the decrementing burst pattern that was characteristic of gasps in control preparations was replaced by bell‐shaped bursts (gasps). In addition, the onset latency to gasping was slightly, but not significantly, decreased. These data suggest that in more mature rats, the role of NO in gasp timing is fundamentally different than that observed in younger rats. Additionally, NO may play an important role in establishing the pattern of ischemia‐induced gasps in this preparation. Supported by HL63175.
Oxygen sensitivity of rhythmogenesis originating from the preBötzinger complex is not a fixed property
Authors: Garcia Alfredo J. , Zanella Sebastien , Woo Susan , Ramirez Jan‐Marino
Published: June 2021

The role of neuronal O2 sensitivity in the preBötzinger complex (preBötC) is best demonstrated by network reconfiguration from fictive eupnea to gasping during hypoxic exposure. Here we demonstrate that the preBötC responds to relative rather than absolute changes in O2, and that the pattern of O2 exposure (sustained versus intermittent) can alter the network response to neuromodulators. Experiments employing either sustained or intermittent exposure to 0.50 or 0.95ATA O2 were conducted in the preBötC isolated in neonatal brainstem slices. Tissue O2 profiles demonstrate that neither 0.50 nor 0.95 ATA O2 produce anoxic conditions. Extracellular recordings reveal that preconditioning at 0.95 ATA O2 (10min) followed by exposure to sustained 0.50 ATA O2 leads to network reconfiguration similar to the transition from fictive eupnea to gasping. In contrast, slices maintained only in 0.50 ATA O2 possessed stable rhythms similar to fictive eupnea. Moreover, the state of oxygenation also alters the responsiveness to neuromodulation. Antagonism of 5‐HT2A receptors disrupts the rhythm at 0.50 ATA O2 when preconditioned with 0.95ATA O2 but not the rhythm maintained only in 0.50 ATA O2. While norepinephrine stabilizes rhythmogenesis following sustained exposure low levels of O2, following intermittent exposure, norepinephrine destabilizes network activity. These findings demonstrate that both the pattern and history of O2 exposure impact neuromodulation and rhythmogenesis in the preBötC. These forms of plasticity have clinical implications in the context of sleep apnea and re‐oxygenation.
Role of the pre‐Bötzinger Complex in opioid‐induced respiratory depression in adult rats in‐vivo
Authors: Montandon Gaspard , Horner Richard L
Published: June 2021

Respiratory rhythm is generated by pre‐Bötzinger Complex (PBC) neurons in‐vitro, with destruction of PBC neurons producing ataxic breathing in‐vivo. Activation of µ‐opioid receptors at the PBC decreases respiratory rate in neonatal rats in‐vitro, but the role of the PBC in opioid‐induced respiratory depression has not been tested in‐vivo. We recorded diaphragm and genioglossus (GG) muscle activities in adult rats with drugs applied to the PBC region by microdialysis probes. In anesthetized rats (n=6), application of the µ‐opioid receptor agonist fentanyl (100 µM) to the PBC decreased respiratory rate (mean = 43%, p=0.004) and GG activity (mean = 61%, p=0.007), with this depression reversed by the antagonist naloxone (100 µM). The time delay for fentanyl‐induced respiratory depression was correlated with the distance of the probe site from the PBC (r2 = 0.83). Preliminary data in 2 freely behaving rats showed that fentanyl (150 µM) at the PBC also reduced respiratory rate in non‐REM sleep (~30%) but not wakefulness (~3%). The respiratory rate depression produced by fentanyl at the PBC also occurred with subcutaneous fentanyl (0.02‐0.1 mg/kg) in anesthetized and freely behaving rats (mean decreases 30‐54%, p<0.05). These data show that opioid‐sensitive neurons in the PBC mediate suppression of respiratory rate in‐vivo, with responses to µ‐opioid receptor agonists being prominent in non‐REM sleep and anesthesia.
Carbachol injections in the nucleus pontis oralis elicit REM sleep‐like depression of XII nerve activity in the rat in situ perfused working heart‐brainstem preparation (WHBP)
Authors: Brandes Ivo F. , Stettner Georg , Kubin Leszek , Dutschmann Mathias
Published: June 2021

Patients with obstructive sleep apnea suffer from nocturnal episodes of upper airway collapse and hypoxia that is most severe during rapid‐eye‐movement sleep (REMS). The XII activity is diminished and the upper airway muscle tone is reduced. To study the central neural mechanisms of REMS, in vivo pharmacological models have been used (Kubin, 2001). To test whether upper airway motor tone depression can be also elicited in the in situ rat WHBP, carbachol (25‐50 nl, 10mM) was injected into the pons in n=33 WHBPs while recording XII and phrenic nerve activities (PNA). In 23 preparations, depression of XII nerve activity lasting 16‐24 min occurred within 142 s ± 26. The depressant episodes could be elicited repeatedly by injections at the same site at >30 min intervals. Histological analysis revealed effective injection sites in the nucleus pontis oralis, Bregma ‐8.16 to ‐8.76, (Paxinos and Watson, 2005). Ineffective injection sites were either located in the nucleus pontis caudalis, were too ventral or too lateral. Only carbachol injections into the nucleus pontis oralis trigger REMS like alterations of the breathing pattern in the WHBP.

Funded by BCCN Göttingen and HL‐47600.
Role of respiratory system impedance in the difference of ventilatory control between children and adults.
Authors: Keslacy Stefan , Carra Juliette , Ramonatxo Michelle
Published: June 2021

How children are able to adapt their ventilation to the intensity of exercise faster than adults remain unclear. We hypothesized that differences of VE observed between children and adults depend on either peripheral chemoreceptors or central command activity. We examined ventilatory control parameters in either normoxic or hypoxic condition (FIO2 = 0.15). We analyzed the adaptability of the respiratory exchanges by (i) the measurement of ventilatory kinetics time‐constant and (ii) the central command by the mouth‐occlusion pressure (P0.1). A group of nine pre‐pubescent children (mean age 9.5 ± 1 years) and a group of eight adults (mean age 24 ± 3.1 years) performed a constant‐load exercise. In normoxia, children had significantly shorter time‐constant (τ)VCO2 (respectively 38.5 ± 4.3s and 53.1 ± 5.3s; P<0.001), τVE (respectively 52.5 ± 13.1s vs. 66.1 ± 12.3s; P<0.001), and τP0.1 (57.4 ± 15.4s and 61.0 ± 12.9s, respectively; P<0.001) than adults. In hypoxia, children exhibited shorter τP0.1/VT/Ti compare to adults. Reinforced by the significant correlation between τVE and τP0.1/VT/Ti for children but not adults, we concluded that ventilatory response differences could be due in part to the respiratory system impedance.
Prenatal LPS exposure reduced offspring mother's recognition in infancy by olfactory cues
Authors: Taricano Marina , Kirsten Thiago Berti , Palermo‐Neto João , Silva Maria Teresa Araujo , Bernardi Maria Martha
Published: June 2021

Pre or perinatal events influencing maternal and offspring interactions might contribute to the development of behavioral or neuropsychiatric disorders. This study investigated the relationships of maternal‐sickness behavior during pregnancy in offspring development and in the olfactory system preferences in infancy and adulthood. Pregnant Wistar rats were administered with lipopolysaccharide (LPS, 100 µg/kg, i.p.) on gestation day (GD) 9.5. Dam's sickness behavior was analyzed, and at birth, the offspring number and weight were recorded. Male offspring were evaluated through physical development, and the olfactory preference at the 7th and 90th days of life. Relative to control group, the results showed that LPS treatment : 1) decreased the open‐field behavior, food intake, and weight gain of dams, but no pyrexia; 2) reduced the number of rat pups, but did not alter the physical development; 3) reduced the mother recognition by the olfactory test infancy; 4)did not modify the offspring olfactory preference in adulthood. These data revealed that prenatal LPS reduced mothers pup's recognition by olfactory cues when in infancy, but this alterations did not remain in adulthood.
Prenatal LPS exposure increases offspring anxiety and improves learning reversion in a skinner task
Authors: Taricano Marina , Palermo‐Neto João , Silva Maria Teresa Araujo , Bernardi Maria Martha
Published: June 2021

Lipopolysaccharide (LPS) has been associated with adverse developmental outcome, including neurological injury and might contribute to the development of behavioral or neuropsychiatric disorders, including schizophrenia and autism. This study investigated the relationships of perinatal administration of LPS on open field task (OPT), elevated plus maze (EPM) and on learning in the Skinner box (CB). For this, pregnant Wistar rats received intraperitoneal LPS (100µg/Kg) at the 9.5th day of pregnancy. Male offspring were evaluated in the sixty day after birth in the OPT, and in the ninety days of age in the EPM and CB test. In relation to control group, the results showed that LPS treatment: 1) an increased time and frequency of freezing and similar general activity in open field task; 2) a decreased time in the EPM open arms and 3) no difference in the time of the acquisition of learning but a shorter period of time to revert the learning in CB. Data from EPM and OPT revealed that LPS administered at GD 9.5 increased offspring anxiety and emotionality at adult age. These facts, probably, improved the time of learning reversion observed in the CB test.
Fyn limits the protease activating receptor‐1 (PAR‐1)‐induced increase in lung microvascular permeability by inducing FAK activation
Authors: Knezevic Nebojsa , Tauseef Mohammad , Thennes Tracy , Mehta Dolly
Published: June 2021

We showed that focal adhesion kinase (FAK) is required to reverse the thrombin‐induced increase in endothelial permeability. Fyn is a non‐receptor Src family tyrosine kinase, which phosphorylates FAK. We investigated the role of Fyn in regulating lung microvascular permeability using Fyn deficient mice. First, we determined whether activation of PAR‐1 by specific activating peptide (TFLLRN), alters FAK activity in lungs. Lungs of WT or Fyn−/− mice received i.v. injection of either control or PAR‐1 activating peptide were homogenized for determination of FAK phosphorylation. We observed that PAR‐1 agonist peptide increased FAK phosphorylation at Y397 and Y576 in WT mice lungs, but failed to induce FAK phosphorylation in lungs of Fyn−/− mice. Next, we determined microvessel filtration coefficient (Kf,c) in lungs isolated from WT and Fyn−/− mice. We observed that basal Kf,,c was significantly higher in Fyn−/− lungs than WT lungs. We also determined Evans blue albumin extravasation and lung wet‐ to dry weight ratio following PAR‐1 activation to assess the role of Fyn in regulating lung edema formation. Injection of PAR‐1 peptide produced significantly greater increase in lung vascular permeability in Fyn−/− mice, indicating that Fyn limits the PAR‐1‐induced pulmonary edema. We next addressed whether rescuing FAK activation could restore lung vascular permeability in Fyn−/− mice. Liposomes conjugated with FAK double phospho‐mimicing mutant (Y397D/Y576D) were injected in Fyn−/− mice and lung vascular permeability was determined after confirmation of FAK mutant expression. We show that rescuing FAK phosphorylation markedly suppressed PAR‐1 induced lung vascular permeability in Fyn−/− mice. These studies identify Fyn as the critical tyrosine kinase that by inducing FAK activation maintains lung vascular barrier function.