Temperature, cardiovascular mortality, and the role of hypertension and renin-angiotensin-aldosterone axis in seasonal adversity: a narrative review

Association between baseline blood pressure variability and left heart function following short-term extreme cold exposure

Extreme cold exposure has been widely considered as a cardiac stress and may result in cardiac function decompensation. This study was to examine the risk factors that contribute to changes in cardiovascular indicators of cardiac function following extreme cold exposure and to provide valuable insights into the preservation of cardiac function and the cardiac adaptation that occur in real-world cold environment. Seventy subjects were exposed to cold outside (Mohe, mean temperature -17 to -34°C) for one day, and were monitored by a 24-h ambulatory blood pressure device and underwent echocardiography examination before and after extreme cold exposure. After exposure to extreme cold, 41 subjects exhibited an increase in ejection fraction (EF), while 29 subjects experienced a decrease. Subjects with elevated EF had lower baseline coefficients of variation (CV) in blood pressure compared to those in the EF decrease group. Additionally, the average real variability (ARV) of blood pressure was also significantly lower in the EF increase group. Multivariate regression analysis indicated that both baseline CV and ARV of blood pressure were independent risk factors for EF decrease, and both indicators proved effective for prognostic evaluation. Correlation analysis revealed a correlation between baseline blood pressure CV and ARV, as well as EF variation after exposure to extreme cold environment. Our research clearly indicated that baseline cardiovascular indicators were closely associated with the changes in EF after extreme cold exposure. Furthermore, baseline blood pressure variability could effectively predict alterations in left cardiac functions when individuals were exposed to extreme cold environment.

Isorhynchophylline improves lipid metabolism disorder by mediating a circadian rhythm gene Bmal1 in spontaneously hypertensive rat

Hypertension is a progressive metabolic disease characterized by circadian regulation of lipid metabolism disorder. Identifying specific lipid components and maintaining circadian homeostasis of lipid metabolism might be a promising therapeutic strategy for hypertension. Isorhynchophylline (IRP) can regulate lipid metabolism; however, the underlying mechanism of IRP in improving lipid metabolism rhythm disorder is still unclear. The lipid circadian biomarkers and abnormal metabolic pathways intervened by IRP were investigated using diurnal lipidomic research methods. The 24-h circadian changes in mRNA and protein expression levels of circadian genes, including Bmal1, Clock, Cry1, Cry2, Per1, and Per2, and lipid metabolism-related factors (PPARα and LPL) were determined using RT-PCR and western blot analyses, respectively. The underlying mechanisms were intensively investigated by inhibiting Bmal1. Molecular docking and drug affinity responsive target stability analyses were performed to assess the binding affinity of IRP and Bmal1. IRP treatment could effectively improve 24-h blood pressure, ameliorate the lipid metabolic rhythm disorder, reverse the expression levels of circadian rhythm genes, and regulate lipid metabolism-related genes (PPARα and LPL) by mediating Bmal1. This study highlighted the potential effects of IRP in maintaining the circadian homeostasis of lipid metabolism and the treatment of hypertension.

The Modern Environment: The New Secondary Cause of Hypertension?

The most important risk factor for cardiovascular disease, the leading cause of death worldwide, is hypertension. Although most cases of hypertension are thought to be essential, the multifactorial associations of the environmental influence on blood pressure seem to play an important role and should be more closely investigated. This review attempts to focus on the recent literature that examines the environmental effects on arterial blood pressure and its management. Seasonal variability and the role of ambient temperature, either occupational or recreational noise pollution, as well as obesity due to environment-caused dietary habits, are recognized as important risk factors, affecting the onset as well as the regulation of hypertension. Furthermore, the effects of seasonal fluctuations in blood pressure, noise pollution, and obesity seem to share a similar pathogenesis, and as such to all further react together, leading to increased blood pressure. The activation of the autonomous nervous system plays a key role and causes an increase in stress hormones that generates oxidative stress on the vascular system and, thus, vasoconstriction. In this review, by focusing on the association of the environmental impact with arterial blood pressure, we come to the question of whether most cases of hypertension-if not all-should, indeed, be considered primary or secondary.