scholarly journals Leptin: Mechanisms Involved In Signaling and Resistance

2021 ◽  
pp. 1-5
Author(s):  
Touqeer Anjum ◽  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Genetic Mutation ◽  
Leptin Resistance ◽  
Energy Availability ◽  
Inflammatory Signaling ◽  
Nonpharmacological Treatment ◽  
White Adipocyte ◽  
Biological Aspects ◽  
Acute Changes

Leptin is secreted mainly by white adipocyte tissue, and it circulates at levels positively correlated with fat mass, thus reflecting primarily the amount of energy stored in adipose tissue. Leptin levels also change with acute changes in energy intake and thus, secondarily reflect acute energy availability. Several potential mechanisms behind leptin resistance have been identified including: Inflammatory signaling, elevated free fatty acids, high leptin and genetic mutation in OB and DBU genes. This review summaries all the physiological, biological aspects of leptin hormone including increases energy expenditure, thermogenesis, heart rate, blood pressure but decreases glycaemia. This review summarizes the pharmacological and nonpharmacological treatment of leptin hormone imbalances.

Repeatability of Spectral Components of Short-Term Blood Pressure and Heart Rate Variability during Acute Sympathetic Activation in Healthy Young Male Subjects

1997 ◽  
Vol 93 (1) ◽  
pp. 21-28 ◽  
Author(s):  
Laure Cloarec-Blanchard ◽  
Christian Funck-Brentano ◽  
Margorzata Lipski ◽  
Patrice Jaillon ◽  
Isabelle MacQuin-Mavier
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Heart Rate Variability ◽  
Clinical Studies ◽  
Low Frequency ◽  
Young Male ◽  
Sympathetic Activation ◽  
Spectral Components ◽  
Acute Changes ◽  
Normalized Units

1. Changes in the low-frequency (LF) components of blood pressure and heart rate variability and in the ratio of LF to high-frequency (HF) components of heart rate variability (LF/HF ratio) are used to assess acute changes in sympathetic control of blood pressure or heart rate and in sympathovagal balance that occur in response to physiological or pharmacological stimuli. Before these spectral indexes can be used to assess the effects of drug therapy or other clinical interventions on reflex sympathetic activity, their repeatability must be evaluated. 2. Intra-observer repeatability was studied by analysing changes in the LF components (expressed as absolute or normalized units) of cardiovascular variability and in the LF/HF ratio during sympathetic activation induced by nitroglycerin infusion (n = 10 subjects) or 60° head-up tilt (n = 13 subjects) repeated on two occasions, 2 days and 1 week apart respectively, in healthy young male volunteers. Repeatability was estimated as recommended by Bland and Altman. 3. Bland and Altman's plots of the repeatability of changes in the LF components and LF/HF ratio showed that measurements were sufficiently repeatable to be used over periods of time of up to 1 week in clinical studies. 4. The sample-size tables derived from our results show that expression of spectral components as normalized units, and use of a cross-over design, minimize the number of subjects to be included in clinical studies conducted using similar designs and LF component changes as endpoints.

scholarly journals Interaction between graviception and carotid baroreflex function in humans during parabolic flight-induced microgravity

2018 ◽  
Vol 125 (2) ◽  
pp. 634-641 ◽  
Author(s):  
Shigehiko Ogoh ◽  
Michaël Marais ◽  
Romain Lericollais ◽  
Pierre Denise ◽  
Peter B. Raven ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Parabolic Flight ◽  
Central Blood Volume ◽  
Pressure Regulation ◽  
Baroreflex Function ◽  
Carotid Baroreflex ◽  
Acute Changes

The aim of the present study was to assess carotid baroreflex (CBR) function during acute changes in otolithic activity in humans. To address this question, we designed a set of experiments to identify the modulatory effects of microgravity on CBR function at a tilt angle of −2°, which was identified to minimize changes in central blood volume during parabolic flight. During parabolic flight at 0 and 1 g, CBR function curves were modeled from the heart rate (HR) and mean arterial pressure (MAP) responses to rapid pulse trains of neck pressure and neck suction ranging from +40 to −80 Torr; CBR control of HR (carotid-HR) and MAP (carotid-MAP) function curves, respectively. The maximal gain of both carotid-HR and carotid-MAP baroreflex function curves were augmented during microgravity compared with 1 g (carotid-HR, −0.53 to −0.80 beats·min−1·mmHg−1, P < 0.05; carotid-MAP, −0.24 to −0.30 mmHg/mmHg, P < 0.05). These findings suggest that parabolic flight-induced acute change of otolithic activity may modify CBR function and identifies that the vestibular system contributes to blood pressure regulation under fluctuations in gravitational forces. NEW & NOTEWORTHY The effect of acute changes in vestibular activity on arterial baroreflex function remains unclear. In the present study, we assessed carotid baroreflex function without changes in central blood volume during parabolic flight, which causes acute changes in otolithic activity. The sensitivity of both carotid heart rate and carotid mean arterial pressure baroreflex function was augmented in microgravity compared with 1 g, suggesting that the vestibular system contributes to blood pressure regulation in humans on Earth.

scholarly journals Transmitral velocities measured by pulsed Doppler in healthy volunteers: effects of acute changes in blood pressure and heart rate.

Heart ◽  
1989 ◽  
Vol 61 (4) ◽  
pp. 344-347 ◽  
Author(s):  
S A Smith ◽  
J E Stoner ◽  
A E Russell ◽  
J M Sheppard ◽  
P E Aylward
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Healthy Volunteers ◽  
Pulsed Doppler ◽  
Acute Changes

Exercise and platelet intracellular free calcium concentration

1988 ◽  
Vol 75 (2) ◽  
pp. 221-224 ◽  
Author(s):  
Susan M. Barr ◽  
Kennedy R. Lees ◽  
Daniel D. McBryan ◽  
James Reid ◽  
Elizabeth Farish ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Calcium Concentration ◽  
Bicycle Ergometer ◽  
Intracellular Free Calcium ◽  
Free Calcium ◽  
Intracellular Free Calcium Concentration ◽  
Free Calcium Concentration ◽  
Acute Changes ◽  
Pressure Changes

1. A positive correlation between blood pressure and platelet intracellular free calcium concentration ([Ca2+]i) has been reported. We examined the effect of acute changes in blood pressure associated with exercise on platelet [Ca2+]i. 2. Twenty-one subjects had blood pressure and heart rate readings taken after 60 min rest, and subjects were then exercised on a bicycle ergometer at 120 W for 30 min. Blood pressure and heart rate readings were repeated immediately after exercise, 30 min after exercise, and then after a further hour. Blood samples were taken after each set of blood pressure and heart rate readings for catecholamine, lactate and platelet [Ca2+]i estimations. 3. There were significant increases in systolic and diastolic blood pressure, heart rate, and plasma lactate and catecholamine levels during the course of the study. There were no significant changes in platelet [Ca2+]i. 4. These results suggest that the acute blood pressure changes related to exercise are not associated with a change in platelet [Ca2+]i.

Caffeine and Placebo Expectation

2007 ◽  
Vol 21 (2) ◽  
pp. 91-99 ◽  
Author(s):  
Yunfeng Sun ◽  
Yinling Zhang ◽  
Ning He ◽  
Xufeng Liu ◽  
Danmin Miao
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Sleep Deprivation ◽  
Cognitive Performance ◽  
Cognitive Functions ◽  
Cardiovascular Regulation ◽  
Double Blind ◽  
Positive Effects ◽  
Pressure Tests ◽  
Healthy Males

Abstract. Caffeine placebo expectation seems to improve vigilance and cognitive performance. This study investigated the effect of caffeine and placebo expectation on vigilance and cognitive performance during 28 h sleep deprivation. Ten healthy males volunteered to take part in the double-blind, cross-over study, which required participants to complete five treatment periods of 28 h separated by 1-week wash-out intervals. The treatments were no substance (Control); caffeine 200 mg at 00:00 (C200); placebo 200 mg at 00:00 (P200); twice caffeine 200 mg at 00:00 and 04:00 (C200-C200); caffeine 200 mg at 00:00 and placebo 200 mg at 04:00 (C200-P200). Participants were told that all capsules were caffeine and given information about the effects of caffeine to increase expectation. Vigilance was assessed by a three-letter cancellation test, cognitive functions by the continuous addition test and Stroop test, and cardiovascular regulation by heart rate and blood pressure. Tests were performed bihourly from 00:00 to 10:00 of the second day. Results indicated that C200-P200 and C200-C200 were more alert (p < .05) than Control and P200. Their cognitive functions were higher (p < .05) than Control and P200. Also, C200-P200 scored higher than C200 in the letter cancellation task (p < .05). No test showed any significant differences between C200-P200 and C200-C200. The results demonstrated that the combination of caffeine 200 mg and placebo 200 mg expectation exerted prolonged positive effects on vigilance and cognitive performance.

Reduction in Pain Sensitivity from Pharmacological Elevation of Blood Pressure in Persons with Chronically Low Blood Pressure

2009 ◽  
Vol 23 (3) ◽  
pp. 104-112 ◽  
Author(s):  
Stefan Duschek ◽  
Heike Heiss ◽  
Boriana Buechner ◽  
Rainer Schandry
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Pain Sensitivity ◽  
Pain Threshold ◽  
Pain Perception ◽  
Drug Effects ◽  
Pressure Effects ◽  
Double Blind ◽  
Low Blood Pressure ◽  
Present Trial

Recent studies have revealed evidence for increased pain sensitivity in individuals with chronically low blood pressure. The present trial explored whether pain sensitivity can be reduced by pharmacological elevation of blood pressure. Effects of the sympathomimetic midodrine on threshold and tolerance to heat pain were examined in 52 hypotensive persons (mean blood pressure 96/61 mmHg) based on a randomized, placebo-controlled, double-blind design. Heat stimuli were applied to the forearm via a contact thermode. Confounding of drug effects on pain perception with changes in skin temperature, temperature sensitivity, and mood were statistically controlled for. Compared to placebo, higher pain threshold and tolerance, increased blood pressure, as well as reduced heart rate were observed under the sympathomimetic condition. Increases in systolic blood pressure between points of measurement correlated positively with increases in pain threshold and tolerance, and decreases in heart rate were associated with increases in pain threshold. The findings underline the causal role of hypotension in the augmented pain sensitivity related to this condition. Pain reduction as a function of heart rate decrease suggests involvement of a baroreceptor-related mechanism in the pain attrition. The increased proneness of persons with chronic hypotension toward clinical pain is discussed.

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