Physiologic regulation of heart rate and blood pressure involves connexin 36–containing gap junctions

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.

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

Journal of Psychophysiology ◽

10.1027/0269-8803.23.3.104 ◽

2009 ◽

Vol 23 (3) ◽

pp. 104-112 ◽

Cited By ~ 12

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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Sex Differences in Cardiovascular Reactivity

Journal of Psychophysiology ◽

10.1027/0269-8803.23.2.77 ◽

2009 ◽

Vol 23 (2) ◽

pp. 77-84 ◽

Cited By ~ 11

Author(s):

Matthew C. Whited ◽

Kevin T. Larkin

Keyword(s):

Blood Pressure ◽

Heart Rate ◽

Sex Differences ◽

Gender Roles ◽

Cardiovascular Reactivity ◽

Task Type ◽

Conflict Task ◽

Men And Women ◽

Conflicting Evidence ◽

Blood Pressure Responses

Sex differences in cardiovascular reactivity to stress are well documented, with some studies showing women having greater heart rate responses than men, and men having greater blood pressure responses than women, while other studies show conflicting evidence. Few studies have attended to the gender relevance of tasks employed in these studies. This study investigated cardiovascular reactivity to two interpersonal stressors consistent with different gender roles to determine whether response differences exist between men and women. A total of 26 men and 31 women were assigned to either a traditional male-oriented task that involved interpersonal conflict (Conflict Task) or a traditional female-oriented task that involved comforting another person (Comfort Task). Results demonstrated that women exhibited greater heart rate reactions than men independent of the task type, and that men did not display a higher reactivity than women on any measure. These findings indicate that sex of participant was more important than gender relevance of the task in eliciting sex differences in cardiovascular responding.

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The Effects of a Caffeine Placebo and Experimenter Expectation on Blood Pressure, Heart Rate, Well-Being, and Cognitive Performance

European Psychologist ◽

10.1027//1016-9040.6.1.15 ◽

2001 ◽

Vol 6 (1) ◽

pp. 15-25 ◽

Cited By ~ 18

Author(s):

Harald Walach ◽

Stefan Schmidt ◽

Yvonne-Michelle Bihr ◽

Susanne Wiesch

Keyword(s):

Blood Pressure ◽

Heart Rate ◽

Cognitive Task ◽

Well Being ◽

Control Group ◽

Double Blind ◽

Main Effect ◽

The Difference ◽

Being There ◽

To Receive

We studied the effect of experimenter expectations and different instructions in a balanced placebo design. 157 subjects were randomized into a 2 × 4 factorial design. Two experimenters were led to expect placebos either to produce physiological effects or not (pro- vs. antiplacebo). All subjects except a control group received a caffeine placebo. They were either made to expect coffee, no coffee, or were in a double-blind condition. Dependent measures were blood pressure, heart rate, well-being, and a cognitive task. There was one main effect on the instruction factor (p = 0.03) with the group “told no caffeine” reporting significantly better well-being. There was one main effect on the experimenter factor with subjects instructed by experimenter “proplacebo” having higher systolic blood pressure (p = 0.008). There was one interaction with subjects instructed by experimenter “proplacebo” to receive coffee doing worse in the cognitive task than the rest. Subjects instructed by experimenter “antiplacebo” were significantly less likely to believe the experimental instruction, and that mostly if they had been instructed to receive coffee. Contrary to the literature we could not show an effect of instruction, but there was an effect of experimenters. It is likely, however, that these experimenter effects were not due to experimental manipulations, but to the difference in personalities.

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