Assignment: Effects of E-Adrenoceptor Antagonists on Exercise

Assignment: Effects of E-Adrenoceptor Antagonists on Exercise

Assignment: Effects of E-Adrenoceptor Antagonists on Exercise


Discuss about the Effects of E-Adrenoceptor Antagonists on Exercise Induced Cardiovascular Changes.

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Beta – adrenoceptors are binded  by beta blockers drugs which block the binding of norepinephrine and epinephrine receptors. These cause inhibition of the effects which act on the receptors. Beta blockers act as drugs which are sympatholytic. Often beta blockers bind to beta-adrenoceptors which partially activates the receptors which activates them while offering prevention of norepinephrine from binding the receptor. The partial agonists thus provide backgrounds for sympathetic activity while offering prevention of normal and enhanced sympathetic activity. The beta blockers possess aspect of intrinsic sympathomimetic activity while others produce stabilizing activity, thus producing similar activites as observed on membrane stabilization activity by sodium channels blockers.[i]

Beta blockers bind themselves to beta adrenoceptors which are located in cardiac area surrounding the nodal tissue, which conduct the system and offers contraction of myocytes. The beat has been shown to have both β1 and β2 adrenoceptors, which the common is β1 adrenoceptors. It offers binding effect on the norepinephrine which releases itself to sympathetic nerves located in adrenergic area. Beta blockers in this case offer binding protection to normal ligand β-adrenoceptors through competing itself on the binding sites.[ii]

Beta adrenoceptors are coupled by the Gs protein which offers activation of adenyl cyclase forming Camp located in the ATP which increases the Camp and thus activated the dependent protein kinase. With the general level of sympathetic tone in the heart, these beta blockers are able to lower down the sympathetic influence which offers stimulation of the heart rate, contractility, electrical conduction and relaxation. This leads to reduction in heart rate, contractility, velocity conduction and relaxation. These kinds of drugs have been shown to have an effect on the elevated levels of sympathetic activity.[iii]

With concern of cardiovascular health, beta blockers often offer little vascular effect due to the β2 adrenoceptors having small function of the modulator in the basal vascular tone. Blockage of β2 adrenoceptors is linked to smaller degree of vasoconstriction in the vascular beds.[iv]

Studies have shown that β1 and β2 adrenoceptor receptors are associated increased intensity of vascular activity, it stimulates in response to the constriction and relaxation of the arteries and veins.[v] Endothelial cells are not produced through mediation of β1 and β2 adrenoceptors, rather they play a key role in influcneing blood vessel activity, further the role played the vascular activity is key in prevention and treatment of vascular disease, thus assessing the different morphology of cardiac function is relevant in establishing effects of β1 and β2 adrenoceptors. [vi]

Beta-adrenoceptor antagonists function in cardiovascular management by lowering elevated blood pressure. Compounds such as Atenol selectively apply to Beta 1-adrenoceptor which possess intrinsic sympathomimetic activity. [vii] Pindol on the other hand has non selective ability of beta-adrenoceptor which possesses sympathomimetic activity. These study evaluates its application when used in two body states that is during rest and exercise activities, medical and therapeutic effects of both drugs is being tested. The study is a double blind using vitamin B6 as a placebo control.

This study thus seeks to examine the effects of orally administered β adrenoceptors antagonists, Atenolol and Pendolol on the blood pressure effects, heart rate and lung function during two critical phases of rest and after exercise activity. Assignment: Effects of E-Adrenoceptor Antagonists on Exercise

Methods and materials

The study experiment was submitted to the University of New South Wales, health science department for ethical approval. This experimental study employed double blind design , where subjects were blinded and utilized placebo and control usage. The subject participants involved students aged between 18-65 years of the University of New South Wales.

The materials need for this study included Perceived Exertion Scale, heart rate monitor having watch, strap and polar, blood pressure monitor, peak flow meter and a timer. The experimental phase involved two stages; pre drug and post drug . at the pre drug phase, the start the timer at 0 minutes and time adjusted to resistance level to obtain the KP level, then hold KP level at 50rpm for 2 minutes. During the last 10 seconds, recording of the heart rate, (EHR) and exertion level are undertaken. At 15 minutes recoding s of resting heart rate (RHR) is taken, while at 30 minutes, RHR, oxygen saturation, blood pressure and lung function is undertaken. Then bike exercise undertaken while the KP levels is set at 2 minutes repeat the assessment of EHR, oxygen saturation and exertion levels.

At post drug level, drug is consumed and measurements taken at 15 minutes rest, record thee RHR, oxygen saturation, blood pressure and lung function test for the participant, again the assessments are undertaken at 30 minutes , rest, 45 minutes rest, 60 minutes rest, 75 minutes rest  and 90 minutes rest post drug ingestion rest level . after 90 minutes start the bike then set at KP levels  for 2 minutes then take the assessments of HER, oxygen saturation and exertion level.


Pre drug treatment results

Time/min Resting heart rate


BP- dbp/sbp









  Rest       Exercise    
0 82 115/76 434 98 97 399 10.6
15 87 116/75 441 97      
30 86 113/74 445 97 95 114 11


Average 84 117/75 440 97 97 215 11.2

Table 1 showing the pre drug assessment of the various assessment indicators.

Key ; PEFR(Peak expiratory flow rate), ROS( rate of oxygen saturation ), EOS(Exercise oxygen saturation), HER- (Heart exercise rate)


Post drug treatment results

Time/min SBP/DBP mmHg    
  Vit B6 Atenolol Pendalol
60 117/72 113/69 106/70
90 118/70 107/67 104/65
120 115/69 108/70 101/64
Average 116/71 109/68 103/66

Table 2 showing the blood pressure assessment

Time/min RHR beats/min    
  Vit B6 Atenolol Pendalol
60 79 79.5 71
90 79 79 72
120 82 82 71
Average 80 80 71.

Table 2 : showing resting heart rate

Time/min PEFRL/min    
  Vit B6 Atenolol Pendalol
60 475 451 415
90 460 456 450
120 480 457 451
Average 471 451 438

Table 3 showing the rate of peak expiratory rate

Time/min ROS



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