Nitric oxide and L-type calcium channel influences the changes in arterial blood pressure and heart rate induced by central angiotesin II

The effect of ambient temperature on blood pressure of patients undergoing hemodialysis in the Pantanal-Brazil

The objective was to analyze the association of changes in pre-dialysis systolic and diastolic blood pressure with air temperature in a municipality in the Brazilian Pantanal, a tropical climate area. Longitudinal panel study, with analysis of mixed effects models of 133 hemodialysis patients in the city of Cáceres-Mato Grosso in 2014. Air temperature showed an inverse association with pre-dialysis systolic and diastolic blood pressure. With each increase of 1 °C in the mean air temperature, the pre-dialysis systolic blood pressure decreases -0.730mmHg (p ≤ 0.000) and the pre-dialysis diastolic blood pressure decreases -0.280mmHg (p ≤ 0.000). The estimated effect was greater for systolic blood pressure, but both pre-dialysis blood pressure measures are reduced with an increase in lag (up to two days), even when adjusted for relative air humidity. Air temperature is determinant for changes in pre-dialysis systolic and diastolic blood pressure in hemodialysis patients. The temperature effect was greater for systolic blood pressure than for diastolic blood pressure.

Acute effects of temperature exposure on blood pressure: An hourly level panel study

BACKGROUND

Several epidemiological studies have shown that blood pressure changes with temperature based on the daily temperature and linear relationship assumption. However, little is known about the true curve shape of the relationship between temperature and blood pressure.

OBJECTIVES

The objective of this study was to investigate the non-linear relationship between hourly temperature and blood pressure.

METHODS

This is a prospective panel study comprising 100 participants in Suzhou, China. The blood pressure of each participant was measured >50 times between October 2013 and January 2016. Hourly temperature data were derived from the nearest monitoring station owned by the China Meteorological Administration. A Distributed Lag Nonlinear Model (DLNM) was used to investigate the relationship between hourly temperature and blood pressure.

RESULTS

We found that the relationship between hourly temperature and blood pressure was parabolic. Short-term exposure to hourly temperatures had significant cold and heat effects on systolic blood pressure (SBP), diastolic blood pressure (DBP), pulse pressure (PP), and mean arterial pressure (MAP). The hourly temperature had a significant lag effect on blood pressure, with a lag time of 0-5 h. Alcohol users were more sensitive to the cold effects of hourly temperature, and the diabetic population was more sensitive to the heat effects of hourly temperature on PP.

CONCLUSION

Temperature imparts short-term effects on blood pressure. Therefore, timely protective measures during cold waves or cold weather are beneficial to maintain stable blood pressure levels to reduce the risk of blood pressure related diseases.

Central nitrergic system regulation of neuroendocrine secretion, fluid intake and blood pressure induced by angiotensin-II

BACKGROUND

Nitric oxide (NO) synthesis has been described in several circumventricular and hypothalamic structures in the central nervous system that are implicated in mediating central angiotensin-II (ANG-II) actions during water deprivation and hypovolemia. Neuroendocrine and cardiovascular responses, drinking behavior, and urinary excretions were examined following central angiotensinergic stimulation in awake freely-moving rats pretreated with intracerebroventricular injections of Nω-nitro-L-arginine methyl ester (L-NAME, 40 μg), an inhibitor of NO synthase, and L-arginine (20 ug), a precursor of NO.

RESULTS

Injections of L-NAME or ANG-II produced an increase in plasma vasopressin (VP), oxytocin (OT) and atrial natriuretic peptide (ANP) levels, an increase in water and sodium intake, mean arterial blood pressure and sodium excretion, and a reduction of urinary volume. L-NAME pretreatment enhanced the ANG-II response, while L-arginine attenuated VP and OT release, thirst, appetite for sodium, antidiuresis, and natriuresis, as well as pressor responses induced by ANG-II.

DISCUSSION AND CONCLUSION

Thus, the central nitrergic system participates in the angiotensinergic responses evoked by water deprivation and hypovolemia to refrain neurohypophysial secretion, hydromineral balance, and blood pressure homeostasis.