Waterworks.

Abstract

Having taught for some years in medical school, I still vividly remember the A+ student who collapsed in the library hyperventilating while studying pathological ventilation patterns, definitely a case of too much focussing all of one's attention on the physiology text in front of herself. I have always wondered what happens when they progress to the urine production chapter. Jokes aside, the human urinary tract is a fascinating, tightly regulated organ system. Understanding its function is of increasing relevance for medical caregivers, especially those dealing with ever-ageing patient populations in the Western world. Demographic change forces us to refocus our attention to diseases of the elderly with ever-increasing life expectancies, such as non-neurogenic male lower urinary tract symptoms (Gratzke et al. 2015), overactive bladder symptoms of the elderly (Wolff et al. 2015) and bladder cancer. Age and male gender are the risk factors for bladder cancer, with a median age at diagnosis of 70 years and a male-to-female ratio of 3 : 1. Incidence rates are on the rise, with approx. 380 000 new cases and approx. 150 000 deaths per year worldwide (Knowles & Hurst 2015). Traditionally, the kidney had been one of the hot topics of physiological research, which has increasingly been extending its focus from basic mechanisms and molecular kidney physiology (Svenningsen et al. 2014) to disease mechanisms underlying and/or associated with Western lifestyles and ageing populations, such as essential hypertension (Damkjaer et al. 2014), metabolic syndrome and acute and chronic kidney injury (Seibert et al. 2013, Singer et al. 2013, Svenningsen et al. 2013). Acta Physiologica has recently added to our understanding of lower urinary tract structure and function and its pathophysiology. In 2013, Nevéus & Sillén shared a closer look on the early development of bladder function and disturbances in childhood. Embryonic bladder development starts at an early gestational age. At birth, higher CNS centres control micturition, while control of urinary function develops as the child grows and matures, a process which, for many parents, resembles a rather bumpy, curvy ride. Often, however, simple measures such as parent education and non-medical bladder training help significantly. Continued incontinence or nocturnal enuresis may become major issue for an astonishingly high percentage of parents, as approx. 5–10% of 7-year-old children suffer from daytime incontinence and/or nocturnal enuresis, with some never outgrowing it (Nevéus & Sillén 2013). Bladder problems in childhood increase the risk of developing according dysfunctions in adulthood (Nevéus & Sillén 2013) such as nocturia, which is, due to its multi-factorial aetiopathogenesis, now viewed as a distinct clinical condition rather than a mere symptom (Osman et al. 2013). The excellent articles of both Griffiths & Fowler (2013) and de Groat & Wickens (2013) have shed light on recent insights into the mechanisms and circuits by which the CNS controls micturition. Urothelial signalling cascades give rise to the sensation that initiates the perception of ‘needing to go’ (Birder & Wyndaele 2013), while continence and voiding are controlled in close cooperation of the autonomous and somatic systems (Ochodnicky et al. 2013). When we take a closer look at signalling cascades and events in the lower urinary tract, purinergic signalling pathways are of major importance (Avelino et al. 2013, Birder et al. 2013, Burnstock 2013). Current research on bladder interstitial cells, several different subgroups of which have been recently identified within the bladder wall to be interacting with nerves and smooth muscle and probably critically involved in intercellular communication and key physiological functions (McCloskey 2013), is but one example of an emerging field in research on lower urinary tract structure and function. Both neurodegenerative disease (Feinstein et al. 2015) and traumatic damage to the spinal cord (Thomas et al. 2014, Gomez-Amaya et al. 2015) are often accompanied by urinary tract dysfunction. Improved overall survival of patients suffering from according pathologies are accompanied by an increasing relevance of these dysfunctions, which may severely affect the quality of life and ability to participate in day-to-day activities. Thus, a better understanding of the molecular and (patho-) physiological mechanisms will help provide novel opportunities for prognostic patient evaluation, monitoring and treatment. Time for a comfort break. None.