Circadian catecholamine rhythms in people with normal and raised blood pressure

 - unpicking the role of the sympathetic nervous system

Summary

High blood pressure affects around a third of adults in the UK, although many do not realise it. If high blood pressure goes untreated, there is damage to important organs such as the heart, brain, and kidneys. Prolonged high blood pressure can lead to 'heart failure' - a condition in which the heart is unable to pump enough blood to meet the body's needs, making people breathless and less able to exercise.

The sympathetic nervous system plays an important role in blood pressure control and acts on the heart and blood vessels via the catecholamine neurotransmitters. Normal blood pressure is typically higher during the day-time and lower at night (the circadian rhythm). Loss of night-time dipping and increased day-to-day variability are associated with bad patient outcomes. Defining the circadian rhythm of catecholamine release is crucial to interpreting these observations and designing treatment strategies to reduce cardiovascular events.

Until recently there has been no easy way to assess the circadian rhythm of the sympathetic nervous system. However, new techniques in analytical chemistry and the U-RHYTHM 24-hour tissue hormone sampler device offer an opportunity to address this problem.

We will compare the 24-hour tissue catecholamine levels in participants with normal blood pressure and people with high blood pressure, looking for differences in sympathetic nervous activity which may be driving the high blood pressure. The findings will form the basis of a further PHD fellowship application, where we aim to assess how patient treatment regimens can be optimised based on their individual 24-hour catecholamine profiles.