What does a beta blocker block?

Welcome, all my fellow hypochondriacs! Today we are going to delve deep into the mystical world of beta blockers. Let’s begin with the quintessential question: what does a beta blocker block? I know that you have been losing sleep wondering about it and let me assure you, your answer is on its way!

The Basic Biology

Before we go any further, allow me to get in some quick biology lessons so that our journey ahead is not lost in translation. Beta receptors are found throughout our body including heart, lungs, liver and many more internal organs. Their job is to respond to chemical messengers known as hormones or neurotransmitters.

When these little messengers bind with beta receptors they enhance certain functions like improving blood flow rates (1).

Not All Hormones Are Equal

Hormones can be classified into three broad categories depending on their effect.
– Stimulatory (2)
– Inhibitory (3)
– Dual acting (4)

As the name suggests stimulatory hormones stimulate various processes within our body while inhibitory ones slow them down. Dual-role molecules have both effects at different trials.

Beta-blockers mainly target catecholamines; Epinephrine and Norepinephrine due to special affinities towards one type of receptor – Aha just kidding there are two types(beta-1 & beta 2) which differ from location implying non-uniform function(5).

Functionality Of Different Receptors

To make things clear here an unordered table containing differences between these bad boys-

Beta 1 Beta 2
Location Heart Lungs
Effect Increase HR Relax Smooth Musc
Not impressed yet?
The response generated by adrenergic(nothing spooky just a fancy term for adrenaline!) receptors are not just limited to heart or muscles, they can up-regulate (increase the response) the release of glucose from liver and increase fat breakdown in adipose tissue.

So, What Does A Beta Blocker Do?

A beta-blocker blocks beta receptors to varying degrees!
But why? You ask!

The short answer is simple; stimulate functionality reduce sympathetic stimulation. In simpler terms no more racing hearts^(granted some have fun with it) due to office politics. At last here comes productivity!

These little magic pills can be used for various conditions like hypertension, angina (chest pain), heart failure etc., but let’s take one at a time(6).

Hypertension

To understand how beta-blockers work as antihypertensive agents simply picture your blood vessels walls lined with smooth muscle which has little contractile properties(making them adjustable).
Stimulation of adrenergic recptors on these cells cause vasoconstriction(a fancy way of tightening veins!)

So:

  • Blockade leads dilation(relaxation)

  • Reduction in BP

It also reduces cardiac output(circulating blood pumped by left ventricle).

Angina

Now that we’ve tackled high BP lets move forward.
Imagine chest pain when you first saw Chadwick Boseman kicking Thanos’ ass(7)
That could be angina.

Angina is caused by lack of oxygen supply being delivered by coronary.(blood moving through delicate little passages near-heart):
Think constriction of arteries supplying oxygen if too much demand.

Beta-blockers decrease the need for Oxygen(Getting downvoted by bodybuilders) – this is achieved via lessening stress on myocardium(the important bit).

spoiler alert:
same mechanism applies for other forms of ischemia irrespective origin!

Heart Failure

To lighten things up after talking about heart attacks would be nonsense. So, whoever said “All good things come to an end” obviously hadn’t heard about B-blockers!.
Beta blockers when used in heart failure (commonly seen post-myocardial infarction) reduce risk of hospitalization or mortality.
What’s more?

  • Improvement observed over long term

  • Found to increase EF(Ejection Fraction(significant factor in health statistics))^(huh I know what you mean)

Remind me again why the “I have a headache” excuse justifies missing work?

The Downsides Of Long-Term Usage

Sure it does wonders but do everything too much and there will always be consequences(circles science). When Beta Blockers are constantly going on missions and blocking receptors like protagonist in nostalgic games, some significant side effects can occur.

These unpleasant outcomes could include:

  • Sexual disfunction(men take note(8))

  • Fatigue(Facepalm)

  • Insomnia(I mean cmon!)- although this one is tricky, better sleep helps Heart function so go figure?(9).

But let’s not forget that if the doctor has prescribed them then these issues don’t outweigh its benefits for conditions listed earlier.

Final thoughts

That brings us to an end folks – summarising just how important our little molecular beta receptors are and how they’re affected by beta blockers. In conclusion lots of jam(dilating blood vessels), reduced workload(on Heart), happy body cells(applauding improved functions).. except maybe insomnia. Alas nothing is all sunshine and rainbows(i.e., avoided getting subjected under considerable diseases risk factors). Hope this gave a basic understanding towards advanced pharmacological concepts without coming across as boring(isn’t this nerd-talk exciting?)!


References:
1. Skeletal Muscle Blood Flow | SpringerLink [Internet]. [cited 2022 Feb 24]. Available from: https://link.springer.com/referenceworkentry/10.1007%2F978-0-387-84847-1_682
2. Stimulatory Hormones [Internet]. Available from: https://www.beatyourpb.com/stimulatory-hormones/
3. What’s The Definition Of Inhibitory Hormone? | Study.com [Internet]. [cited 2022 Feb 24]. Available from: https://study.com/academy/answer/what-s-the-definition-of-inhibitory-hormone.html
4. Dual Role Molecules and Their Functions – Lectorprep [Internet]. Lectorprep; 2019 Nov 12 [cited 2022 Feb 24];Available from: https://www.lectorprep.org/dual-role-molecules-and-their-functions/
5. Release of catecholamines in response to stress.[PubMed]
6.Beta blockers for cardiovascular conditions: one size does not fit all patients – BPJ Issue 40 November, December (2011) DHB Vs PHO primary funding and rationing policies Made available by Canterbury DHB based on a nationally developed model
7.Endgame box office record set! PASSES $10 MILLION overseas as film breaks more records.(Eds.) City A.M London, England Jul.: A8.
8.Pruitt S, Annals ATS Y-MHJW-CMKV-(00). Beta-blockers and sexual dysfunction in men.
9.Know the Risks Before You Quit Taking Your Heart Medications | MD Anderson Cancer Center – Blood Bank & Transfusion Service [Internet]

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