Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Areum Kim is active.

Publication


Featured researches published by Areum Kim.


American Journal of Physiology-heart and Circulatory Physiology | 2011

Sex differences in carotid baroreflex control of arterial blood pressure in humans: relative contribution of cardiac output and total vascular conductance

Areum Kim; Shekhar H. Deo; Lauro C. Vianna; George M. Balanos; Doreen Hartwich; James P. Fisher; Paul J. Fadel

It is presently unknown whether there are sex differences in the magnitude of blood pressure (BP) responses to baroreceptor perturbation or if the relative contribution of cardiac output (CO) and total vascular conductance (TVC) to baroreflex-mediated changes in BP differs in young women and men. Since sympathetic vasoconstrictor tone is attenuated in women, we hypothesized that carotid baroreflex-mediated BP responses would be attenuated in women by virtue of a blunted vascular response (i.e., an attenuated TVC response). BP, heart rate (HR), and stroke volume were continuously recorded during the application of 5-s pulses of neck pressure (NP; carotid hypotension) and neck suction (NS; carotid hypertension) ranging from +40 to -80 Torr in women (n = 20, 21 ± 0.5 yr) and men (n = 20, 21 ± 0.4 yr). CO and TVC were calculated on a beat-to-beat basis. Women demonstrated greater depressor responses to NS (e.g., -60 Torr, -17 ± 1%baseline in women vs. -11 ± 1%baseline in men, P < 0.05), which were driven by augmented decreases in HR that, in turn, contributed to larger reductions in CO (-60 Torr, -15 ± 2%baseline in women vs. -6 ± 2%baseline in men, P < 0.05). In contrast, pressor responses to NP were similar in women and men (e.g., +40 Torr, +14 ± 2%baseline in women vs. +10 ± 1%baseline in men, P > 0.05), with TVC being the primary mediating factor in both groups. Our findings indicate that sex differences in the baroreflex control of BP are evident during carotid hypertension but not carotid hypotension. Furthermore, in contrast to our hypothesis, young women exhibited greater BP responses to carotid hypertension by virtue of a greater cardiac responsiveness.


American Journal of Physiology-heart and Circulatory Physiology | 2012

Statin therapy lowers muscle sympathetic nerve activity and oxidative stress in patients with heart failure

Shekhar H. Deo; James P. Fisher; Lauro C. Vianna; Areum Kim; Anand Chockalingam; Matthew C. Zimmerman; Irving H. Zucker; Paul J. Fadel

Despite standard drug therapy, sympathetic nerve activity (SNA) remains high in heart failure (HF) patients making the sympathetic nervous system a primary drug target in the treatment of HF. Studies in rabbits with pacing-induced HF have demonstrated that statins reduce resting SNA, in part, due to reductions in reactive oxygen species (ROS). Whether these findings can be extended to the clinical setting of human HF remains unclear. We first performed a study in seven statin-naïve HF patients (56 ± 2 yr; ejection fraction: 31 ± 4%) to determine if 1 mo of simvastatin (40 mg/day) reduces muscle SNA (MSNA). Next, to control for possible placebo effects and determine the effect of simvastatin on ROS, a double-blinded, placebo-controlled crossover design study was performed in six additional HF patients (51 ± 3 yr; ejection fraction: 22 ± 4%), and MSNA, ROS, and superoxide were measured. We tested the hypothesis that statin therapy decreases resting MSNA in HF patients and this would be associated with reductions in ROS. In study 1, simvastatin reduced resting MSNA (75 ± 5 baseline vs. 65 ± 5 statin bursts/100 heartbeats; P < 0.05). Likewise, in study 2, simvastatin also decreased resting MSNA (59 ± 5 placebo vs. 45 ± 6 statin bursts/100 heartbeats; P < 0.05). In addition, statin therapy significantly reduced total ROS and superoxide. As expected, cholesterol was reduced after simvastatin. Collectively, these findings indicate that short-term statin therapy concomitantly reduces resting MSNA and total ROS and superoxide in HF patients. Thus, in addition to lowering cholesterol, statins may also be beneficial in reducing sympathetic overactivity and oxidative stress in HF patients.


The Journal of Physiology | 2009

Influence of ageing on carotid baroreflex peak response latency in humans

James P. Fisher; Areum Kim; Colin N. Young; Shigehiko Ogoh; Peter B. Raven; Niels H. Secher; Paul J. Fadel

The stability of a physiological control system, such as the arterial baroreflex, depends critically upon both the magnitude (i.e. gain or sensitivity) and timing (i.e. latency) of the effector response. Although studies have examined resting arterial baroreflex sensitivity in older subjects, little attention has been given to the influence of ageing on the latency of peak baroreflex responses. First, we compared the temporal pattern of heart rate (HR) and mean arterial blood pressure (BP) responses to selective carotid baroreceptor (CBR) unloading and loading in 14 young (22 ± 1 years) and older (61 ± 1 years) subjects, using 5 s pulses of neck pressure (NP, +35 Torr) and neck suction (NS, −80 Torr). Second, CBR latency was assessed following pharmacological blockade of cardiac parasympathetic nerve activity in eight young subjects, to better understand how known age‐related reductions in parasympathetic nerve activity influence CBR response latency. In response to NP, the time to the peak increase in HR and mean BP were similar in young and older groups. In contrast, in response to NS the time to peak decrease in HR (2.1 ± 0.2 vs. 3.8 ± 0.2 s) and mean BP (6.7 ± 0.4 vs. 8.3 ± 0.2 s) were delayed in older individuals (young vs. older, P < 0.05). The time to peak HR and mean BP were delayed in young subjects following cardiac parasympathetic blockade (glycopyrrolate). Collectively, these data suggest that ageing is associated with delayed peak cardiovascular responses to acute carotid baroreceptor loading that may be, in part, due to age‐related reductions in cardiac parasympathetic tone.


American Journal of Physiology-regulatory Integrative and Comparative Physiology | 2010

Carotid baroreflex control of arterial blood pressure at rest and during dynamic exercise in aging humans

James P. Fisher; Areum Kim; Colin N. Young; Paul J. Fadel

The arterial baroreflex is fundamental for evoking and maintaining appropriate cardiovascular adjustments to exercise. We sought to investigate how aging influences carotid baroreflex regulation of blood pressure (BP) during dynamic exercise. BP and heart rate (HR) were continuously recorded at rest and during leg cycling performed at 50% HR reserve in 15 young (22 ± 1 yr) and 11 older (61 ± 2 yr) healthy subjects. Five-second pulses of neck pressure and neck suction from +40 to -80 Torr were applied to determine the full carotid baroreflex stimulus response curve and examine baroreflex resetting during exercise. Although the maximal gain of the modeled stimulus response curve was similar in both groups at rest and during exercise, in older subjects the operating point (OP) was located further away from the centering point (CP) and toward the reflex threshold, both at rest (OP minus CP; -10 ± 3 older vs. 0 ± 2 young mmHg, P < 0.05) and during exercise (OP minus CP; -10 ± 2 older vs. 1 ± 3 young mmHg, P < 0.05). In agreement, older subjects demonstrated a reduced BP response to neck pressure (simulated carotid hypotension) and a greater BP response to neck suction (simulated carotid hypertension). In addition, the magnitude of the upward and rightward resetting of the carotid baroreflex-BP stimulus response curve with exercise was ∼40% greater in older individuals. These data indicate that despite a maintained maximal gain, the ability of the carotid baroreflex to defend against a hypotensive challenge is reduced, whereas responses to hypertensive stimuli are greater with advanced age, both at rest and during exercise.


Journal of Applied Physiology | 2012

Effect of sex and ovarian hormones on carotid baroreflex resetting and function during dynamic exercise in humans

Areum Kim; Shekhar H. Deo; James P. Fisher; Paul J. Fadel

To date, no studies have examined whether there are either sex- or ovarian hormone-related alterations in arterial baroreflex resetting and function during dynamic exercise. Thus we studied 16 young men and 18 young women at rest and during leg cycling at 50% heart rate (HR) reserve. In addition, 10 women were studied at three different phases of the menstrual cycle. Five-second pulses of neck pressure (NP) and neck suction (NS) from +40 to -80 Torr were applied to determine full carotid baroreflex (CBR) stimulus response curves. An upward and rightward resetting of the CBR function curve was observed during exercise in all groups with a similar magnitude of CBR resetting for mean arterial pressure (MAP) and HR between sexes (P > 0.05) and at different phases of the menstrual cycle (P > 0.05). For CBR control of MAP, women exhibited augmented pressor responses to NP at rest and exercise during mid-luteal compared with early and late follicular phases. For CBR control of HR, there was a greater bradycardic response to NS in women across all menstrual cycle phases with the operating point (OP) located further away from centering point (CP) on the CBR-HR curve during rest (OP-CP; in mmHg: -13 ± 3 women vs. -3 ± 3 men; P < 0.05) and exercise (in mmHg: -31 ± 2 women vs. -15 ± 3 men; P < 0.05). Collectively, these findings suggest that sex and fluctuations in ovarian hormones do not influence exercise resetting of the baroreflex. However, women exhibited greater CBR control of HR during exercise, specifically against acute hypertension, an effect that was present throughout the menstrual cycle.


Journal of Applied Physiology | 2010

Influence of endurance training on central sympathetic outflow to skeletal muscle in response to a mixed meal

Colin N. Young; Shekhar H. Deo; Areum Kim; Masahiro Horiuchi; Catherine R. Mikus; Grace M. Uptergrove; John P. Thyfault; Paul J. Fadel

Nutrient intake is accompanied by increases in central sympathetic outflow, a response that has been mainly attributed to insulin. Insulin-mediated sympathoexcitation appears to be blunted in insulin-resistant conditions, suggesting that aside from peripheral insulin insensitivity, such conditions may also impair the central action of insulin in mediating sympathetic activation. What remains unclear is whether an insulin-sensitive state, such as that induced by chronic endurance training, alters the central sympathetic effects of insulin during postprandial conditions. To examine this question plasma insulin and glucose, muscle sympathetic nerve activity (MSNA), heart rate, and arterial blood pressure were measured in 11 high-fit [HF; peak oxygen uptake (V(O(2peak))) 65.9 +/- 1.4 ml x kg(-1) x min(-1)] and 9 average-fit (AF; V(O(2peak)) 43.6 +/- 1.3 ml x kg(-1) x min(-1)) male subjects before and for 120 min after ingestion of a mixed meal drink. As expected, the insulin response to meal ingestion was lower in HF than AF participants (insulin area under the curve(0-120): 2,314 +/- 171 vs. 4,028 +/- 460 microIU x ml(-1) x 120(-1), HF vs. AF, P < 0.05), with similar plasma glucose responses between groups. Importantly, following consumption of the meal, the HF subjects demonstrated a greater rise in MSNA compared with the AF subjects (e.g., 120 min: Delta21 +/- 1 vs. 8 +/- 3 bursts/100 heart beats, HF vs. AF, P < 0.05). Furthermore, when expressed relative to plasma insulin, HF subjects exhibited a greater change in MSNA for any given change in insulin. Arterial blood pressure responses following meal intake were similar between groups. Collectively, these data suggest that, in addition to improved peripheral insulin sensitivity, endurance training may enhance the central sympathetic effect of insulin to increase MSNA following consumption of a mixed meal.


Autonomic Neuroscience: Basic and Clinical | 2012

New insights into the effects of age and sex on arterial baroreflex function at rest and during dynamic exercise in humans

James P. Fisher; Areum Kim; Doreen Hartwich; Paul J. Fadel


Journal of Applied Physiology | 2011

Seven days of aerobic exercise training improves conduit artery blood flow following glucose ingestion in patients with type 2 diabetes

Catherine R. Mikus; Seth T. Fairfax; Jessica L. Libla; Leryn J. Boyle; Lauro C. Vianna; Douglas J. Oberlin; Grace M. Uptergrove; Shekhar H. Deo; Areum Kim; Jill A. Kanaley; Paul J. Fadel; John P. Thyfault


Archive | 2015

energy expenditure, and blood flow in trained subjects Effects of short-term inactivity on glucose tolerance,

Paul J. Arciero; Denise L. Smith; John P. Thyfault; Grace M. Uptergrove; Shekhar H. Deo; Areum Kim; Jill A. Kanaley; Paul J. Fadel; Catherine R. Mikus; Seth T. Fairfax; Jessica L. Libla; Leryn J. Boyle; Lauro C. Vianna; J Douglas; Nathan T. Jenkins; M. Harold Laughlin; Frank W. Booth; Michael D. Roberts; Jacob D. Brown; Ryan G. Toedebusch; Jaume Padilla; Jonathan R. Lindner; Scott M. Chadderdon; J. Todd Belcik; Elise Smith; Lindsay Pranger; Paul Kievit; Kevin L. Grove


Archive | 2015

dynamic exercise in humans Resetting of the carotid arterial baroreflex during

R. Boushel; S. Strange; Bengt Saltin; Peter B. Raven; Shigehiko Ogoh; James P. Fisher; Colin N. Young; Paul J. Fadel; Areum Kim; Shekhar H. Deo

Collaboration


Dive into the Areum Kim's collaboration.

Top Co-Authors

Avatar

Paul J. Fadel

University of Texas at Arlington

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Researchain Logo
Decentralizing Knowledge