vasodialation Mechanism of Action
Hello people this nitrates now very very important for exam first see where exactly we are okay we are in the anti and journal and anti skimming drugs chapter we have already covered what angina is types of angina when it happens how do you treat it what are the drugs available in that we are here nitrates okay so nitrates you have short acting long acting
You have glycerol try nitrate isos or by die nitrate and isis or white mononitrate i so solve i’d die nitrate can be given sublingually or orally if it is given sublingually this short acting actually sub yeah okay and i solved by die netted if it is given orally it’s long acting however i think essential drug list has only i so solved by dye nitrate sublingual
Tablets and even isis or by mononitrate sublingual tablets are available let’s try trying it also sublingual travels are available and injections are available okay now how nitrates act there whatever we know so far just let’s take a recap they act on blood vessel and they release nitric oxide which dilates the vessel so they relaxed a smooth muscle and they
Dilates the vessels so there will be cooling off the blood in the vascular area so the veins will have the blood and the venous return to the heart will become penis so the preload on the heart will reduce and some amount of afterglow also will reduce because of arterial dialectician okay so did you understand this much so nitrates usually are combined with
Lot of drugs in this group and you can know all those combinations will come – now the thing you should know about nitrates is it is not given with the diagraph so if a person is taking viagra he should not be taking nitrix as both of them will do way so dilation and the person can go into low bp okay it can be fatal also so let us start off with nitrates now
So nitrates like we said the list i’ll try nightly these two images are depicting lists i’ll try matrix this one is isis or by die nitrates indicating and this one isis or by mononitrate so first of all what you should know listen i’ll try nitrate injection is available here let’s try try nitrate tub sublingual it can be given this is actually in the home for
Spray these are all sublingual tablets okay isis or bide mononitrate isis all bye piyah nitrate okay if you actually look at essential drug list isis or by dinah trait 10 mg isis or bide mononitrate 10 mg tablets are available then you have lesser i’ll try nitrate tablets sublingual and you have let’s try try a nitrate injection nitroglycerin it is scored by mg
Okay so shall we move on so in this video we have to cover the mechanism of actions of nitrates okay this all is mechanism of action only then we have to look at the pharmacokinetics of nitrate and worst drug reactions of nitrate and the interactions of nitrate okay shall we get started guys soma kamisama faction first let’s look at okay so how it works preload
Reduction we already told you how it does preload reduction then after load also some amount it will reduce because of arterial dilatation preload is mainly because of venous dilatation and less venous return to the heart then third points they have mentioned here is redistribution of coronary flow then exact mechanism of relief for angina has been mentioned then
Heart and peripheral blood flow we have to look at that point and other smooth muscles okay so first let us look at these two points nitrate what it does it will release nitric oxide this will stimulate the guanylate cyclase okay increased cc cgmp okay let us see look at the diagram it’s better if you look at the dye this one from jean-bob textbooks or nitrates
They get d nitrated and smooth muscle cell they release nitric oxide they stimulate the 1ll cyclase they increased c gmp so there is dephosphorylation of myosin light shine light chain kinase ml seek a decrease calcium concentration in the cytosol relaxation of the vascular smooth muscle fibers leading to way so dilation leading to pooling of the blood and veins
And a decreased venous return so did you understand this much basically what did you understand nitrates they get dehydrated and smooth muscle cell of the blood vessels there they’ll release nitric oxide this nitric oxide will stimulate the guanine lil cyclists increased c g empty which will be phosphorylation of what will happen the phosphorylation of the myosin
Light-chain kinase ml ck happens mmm lc k be phosphorylation and then decrease in the calcium concentration calcium will reduce and there will be relaxation of smooth muscle fibers of the blood vessel vasodilation venous pooling of blood decreased venous return to the heart that same diagram explained in another textbook kd three-party look at this nitro dilators
They release nitric oxide this is the warn a lil cyclase so it is stimulated so there is increased c gmp because of which the mlc k gets d phosphorylated so it is remaining be phosphorylated so there is no contraction look at this for the normal contraction you need ml ck to get phosphorylated which will convert the myosin light-chain – myosin light chain again
Phosphorylated + actin it will release it will lead to contraction now this phosphorylation cannot happen hence contraction cannot happen so did you understand this if you draw this diagram you will get lot of marks please pause this video for actors this diagram because this is a sure short question for you in the exam so if you can read this it is very good
Let us see how our friend will tell this explain this okay so the nitrates they will release nitric oxide which will stimulate the guanylate cyclase and there will be increased cgmp so the 3 gmp will not allow the ml ck to get phosphorylated if mn ck is phosphorylated it will convert the myosin into my it will lead to my o simplicity and contraction so this step
Will not be allowed by this c gmp cgmp also does one more thing it will inhibit the calcium channel so calcium cannot enter as calcium cannot enter there can be no calcium calmodulin and hence there can be no contraction okay so two things it is doing what are nitrates doing two things it is blocking calcium channel and also it is what is doing to two things it
Is dephosphorylation myosin light-chain kinase okay two things it’s doing guys what you should know here it does not work on the heart right it works only on the vascular systems so right here no action on heart okay way so dilation by smooth muscle relaxation okay other effect it has this other smooth muscles also will relax like bronchi he’s so figgis biliary
Tract etc okay so other smooth muscles also will relax though we are not concerned that much about that at this moment okay all this you will explain no nitric oxide and all that hold on one more diagram from shanwa textbook let’s try to understand this vino dilation arterial dilation why that is more we know dilation let’s see if they have tried to explain
Peripheral pooling of blood decreased venous return too hard decreased preload decrease left and right or in diastolic ventricular volume decreased cardiac work decreased oxygen requirement to myocardium oxygen demand is reduced rt lr r tu la dilatation decreased peripheral resistance rate decreased afterload dilatation of large coronal vessels and collateral
Vessels increased blood flow to ischemic area due to redistribution of coronary blood flow increased oxygen delivery to ischemic area also they have explained almost everything this is decrease of pre preload this is decrees of afterload and as far as the redistribution of the blood in coronary vessels so let’s go back and see so this much we understood preload
Reduction afterload reduction this redistribution of corona if look that is nothing but it will again two ways so dilation coronary arteries again blood will supply me let’s apply to myocardium will increase mechanism of relieved and really financing the same thing heart and peripheral blood flow peripheral resistance will come down other smooth muscles we saw
Bronchus then biliary tract he so figures they’ll also relax okay so i think this much is enough for now this diagram you have to practice guys very important and if you want you can learn some flow charts also this one high straight if you want you can learn this so in the next video let’s meet and discuss the pharmacokinetics for nitrous okay
Transcribed from video
Pharmacology 601 c Nitrates Glyceryl trinitrate Isosorbide dinitrate mononitrate Sublingual By MBBS VPASS
