AIMTo determine the role of area postrema (AP) of rabbit in the regulation of cardiovascular function.

METHODSThe rabbits were anesthetized with intravenous injection of 10% urethane and 1% chloralose, and were artificially ventilated. The changes of mean arterial pressure (MAP) and heart rate (HR) were observed when AP was electrically stimulated with different frequency (10 Hz -80 Hz) and after chemical lesion of CVLM or RVLM, respectively.

RESULTSElectrical stimulation of AP with low frequency (10 Hz, 20 Hz) decreased MAP and HR. Stimulation with high frequency(60 Hz, 80 Hz) increased MAP but decreased HR. The changes in MAP and HR were significantly lower (P < 0.01) after CVLM was destroyed when electrical stimulation of AP with 20 Hz, and both changes of MAP and HR were disappeared (P < 0.01) after RVLM was destroyed when electrical stimulation with 20 and 80 Hz.

CONCLUSIONElectrical stimulation of AP with low frequency decreases MAP and HR, stimulation with high frequency induces an increase in MAP and decreases in HR. The former is probably related to excitation of CVLM, the cardiovascular effects induced by different frequency of electrical stimulation are all resulted from the activation of RVLM.

Animals ; Area Postrema ; physiology ; radiation effects ; Blood Pressure ; radiation effects ; Electric Stimulation ; Heart Rate ; radiation effects ; Male ; Medulla Oblongata ; physiology ; radiation effects ; Rabbits

PURPOSE: In our previous study to investigate autonomic nervous system (ANS) activity due to radio frequency (RF) radiation using heart rate variability (HRV), drowsiness was observed in approximately half of all subjects. Therefore, the usage of HRV with unwanted drowsiness could falsely indicate the effects of RF radiation by mobile phones on the ANS. The objective of this study was to determine which posture is appropriate for accurate HRV analysis for provocation study. MATERIALS AND METHODS: A total of 52 healthy subjects (25 males and 27 females) participated in this experiment. We measured the number of times a subject showed drowsiness or sleep deprivation due to awakening, and analyzed HRV six times over 30 minutes in sitting and recumbent postures, using power spectrum. RESULTS: We employed the ratio of low frequency power to high frequency power (LFP/HFP) to analyze the changes in the ANS. The number of sleep deprivation occurrences in the sitting posture was significantly less than that in the recumbent posture (p<0.01), resulting in smaller increase of LFP/HFP. Although LFP/HFP of the two postures varied with time without any provocation, it was more stable in sitting than in recumbent postures. CONCLUSION: A sitting posture is preferable to a recumbent posture for analyzing HRV, because of decreased drowsiness and sleep deprivation, thereby decreasing variation of LFP/HFP during experiment. Considering the drowsiness, it is also recommended that any experiment should be completed within 15 minutes, if possible.
Adult ; *Electromagnetic Fields ; Female ; Heart Rate/*radiation effects ; Humans ; Male ; *Posture ; Sleep Deprivation/*physiopathology

PURPOSE: The purpose of this study was designed to identify the effects of heat therapy on dysmenorrhea, heat being provided using a far infrared rays heating element. METHODS: The research design for the study was a non-equivalent control group quasi-experimental design. Participants were 22 students for the experimental group, and 26 students for the control group. Data were analyzed using SAS WIN 9.1 program. RESULTS: The experimental group had significantly lower mean scores for menstrual pain, dysmenorrhea, and blood pressure than those in the control group. However, no significant differences were found between two groups for pulse, respiration, and temperature. CONCLUSION: These findings show that thermotherapy was effective for reduction of menstrual pain, dysmenorrhea, and B/P. Therefore, this therapy could be used as a nursing intervention for students with dysmenorrhea.
Abdomen/radiation effects ; Adolescent ; Blood Pressure/physiology ; Body Temperature/physiology ; Child ; Dysmenorrhea/prevention & control/*therapy ; Female ; Heart Rate/physiology ; *Hot Temperature ; Humans ; *Infrared Rays ; Respiration

BACKGROUNDThe exaggerated surge in morning blood pressure (BP) that many patients experience upon awakening may be closely related to target organ damage and may be a predictor of cardiovascular complications. However, no previous studies have evaluated the rate of this surge independently of the evening period. It remains unclear whether the rate of increase experienced during the surge is a significant or independent determinant of cardiovascular events.

METHODSWe randomly selected 340 ambulatory BP monitoring (ABPM) patients. All subjects without type 2 diabetes mellitus were divided into two groups: hypertensive group (n = 170) and normotensive group (n = 170). We analyzed ambulatory blood pressure recordings using a double logistic curve-fitting procedure to determine whether the magnitude of the surge in BP and heart rate (HR) in the morning is related to the level of BP in hypertensive individuals. We evaluated the association between the rate of the morning surge in systolic BP (SBP) and the incidence of myocardial infarction and stroke in normotensive and hypertensive subjects.

RESULTSComparisons between hypertensive and normotensive subjects showed that the rates of the morning surges in SBP, mean BP (MBP), and diastolic BP (DBP) were greater in the hypertensive group (P < 0.05) than in the normotensive group. The rate of morning surge in BP was found to be correlated with the daytime SBP (r = 0.236, P < 0.01), the difference between the day and night plateau (r = 0.249, P < 0.01), and the night SBP (r = -0.160, P < 0.05), respectively. After controlling for age, sex, and mean systolic pressure within 24 hours (24 h SBP), the rate of morning surge in SBP was closely correlated with daytime SBP (r = 0.463, P < 0.001), night SBP (r = -0.173, P < 0.05), and the difference between the day and night plateau (r = 0.267, P < 0.001). Logistic regression analysis revealed that the rate of morning surge in SBP was an independent determinant of myocardial infarction (OR = 1.266, 95% CI = 1.153 - 1.389, P < 0.001) and stroke (OR = 1.367, 95% CI = 1.174 - 1.591, P < 0.001).

CONCLUSIONSThe rate of the morning surge in BP is greater in hypertensive subjects than in normotensive subjects. Daytime SBP may be the best predictor of the rate of morning surge in SBP. The rate of the morning surge in BP is associated with cardiovascular and stroke events.

Adult ; Aged ; Blood Pressure ; physiology ; Blood Pressure Monitoring, Ambulatory ; Circadian Rhythm ; physiology ; Female ; Heart Rate ; radiation effects ; Humans ; Hypertension ; physiopathology ; Male ; Middle Aged ; Stroke ; physiopathology