Is Noradrenaline A Friend or Foe of the Kidneys
Adrenaline And Noradrenaline Hormones
The stress hormones adrenaline and noradrenaline are also called the fight-or-flight hormones and they prepare the body for action in the face of physical or emotional threat. Adrenaline is responsible for the rise in pulse rate, rapid breathing and a thumping heart. Noradrenaline prepares the body to undertake either of the choices of ‘fight or flight’ by ‘warming up’ the two preferred organs of the human body, namely the brain and the heart.
In the brain, noradrenaline increases alertness, promotes vigilance and focuses attention. In the heart, it increases blood pressure and pulse rate. In the rest of the body, it triggers the release of glucose from energy stores and increases blood flow to the muscles.
Understanding The ‘Fight-Or-Flight’ Response
Just imagine that you are walking down a deserted street at two o’clock at night in one of the most dangerous and lawless cities in the world. It’s a cold, chilly, starless winter night, the streetlights are oft and it is as dark as the mood of a perennially depressed pessimist. There is no one in sight and the moon is bashfully hidden behind a storm cloud. The only sound you can hear is the howling of a pack of stray dogs as they complain about their low lying position in the evolutionary food chain and of course your own timid footsteps.
You turn a corner and gasp out loud, because just five feet away, straddling the centre of the street, are half a dozen homeless youth. By the light of their cigarettes, you can see multiple piercings, tattoos and a couple of machetes dangling from muscular arms and even a pistol or two. The deep drags they take on their cigarettes light up their vicious, scowling visages. Just when you think it couldn’t possibly get worse, it suddenly does
You hear a shuffling noise behind you and spin around to see a couple of hefty individuals sidle out of a dark alley behind you. They are well over six feet tall and the sharp butcher’s knives look like toothpicks in their massive hands. Your body reacts automatically. Your pulse rate shoots up, your mouth turns dry, you start breathing fast and you can feel your heart thumping loud Though seemingly physically paralysed, your mind is racing at full speed, deciding which will be a better option between the ‘fight-or-flight,’ response.
Disease – A Physiological Threat
Though these stress hormones adrenaline and noradrenaline (responsible for the physical response you experience) are worth their weight in gold when released in the face of physical threat, they are detrimental to the body, it released unnecessarily when the body is not in physical danger. This is what happens during periods of physiological threat.
Physiological threat refers to disease and this could be due to dysfunction of any organ in the body. Here, noradrenaline diverts blood from what it perceives as ‘non-vital’ organs like the kidneys, lungs, liver, bladder and the gut. This drains essential nutrients from these organs putting them in danger of shutdown.
Impact Of Noradrenaline On The Kidneys
Noradrenaline is very closely related to the kidneys. The very word ‘noradrenaline’ in Greek means alongside the kidneys.’ Till recently, there was a lot of controversy in the medical field about the impact of noradrenaline on the kidneys. Many medical experts could not decide it noradrenaline was a friend or an enemy of the kidneys.
On the one hand, during times of mild physiological stress like organ injury, noradrenaline appeared to be an enemy of the kidneys, by pushing blood away from them towards the brain and heart. On the other hand, during times of extreme physiological stress like sepsis (meaning severe infection which has invaded the bloodstream and is damaging all vital organs like liver, kidneys, and lungs), noradrenaline appeared to be a friend of the kidneys, by shunting blood from all organs, increasing the blood pressure and improving blood supply to three preferred organs – the brain, heart, and kidneys!
Though adrenaline and noradrenaline are worth their weight in gold when released in the face of physical threat, they are detrimental to the body if released unnecessarily when the body is not in physical danger
The Paradox Is Resolved
For a long time, this paradox continued to confuse medical researchers. How could the same hormone protect the kidneys during times of extreme stress and yet injure it during times of mild stress? Finally, in 1999, after a series of elegant experiments on dogs, a group of critical care physicians proved beyond doubt, that noradrenaline indeed protects the kidneys when they really need it at times of severe stress, especially sepsis. Literally conforming to the phrase, a friend ¡n need is a friend indeed!’ Today, noradrenaline is a part of the standard care process for patients with sepsis and is used all over the world, to protect kidneys in this situation.
Footnote
In the scenario described in this article – ‘flight’ and not ‘fight’ is definitely a wiser option, unless you happen to be wolverine or Iron Man or some such superhero!