Telechargé par majhouleseri

cadiovascular system

Receptors of tissue of
cardiovascular system and the
points of attachement of drugs
cardiovascular tissue
alpha-adrenergic reseptors
Beta-adrenergic reseptors
cardiovascular tissue:
 Cardiovascular tissue has an important
role in circulating blood for the transport
of oxygen, carbon dioxide, nutrients, blood cells, and
hormones, to maintain the homeostasis of human
body, In particular, vascular grafts with
nanostructured surfaces can promote cell adhesion
and proliferation
 Cardiac muscle tissue is an extremely specialized
form of muscle tissue that has evolved to pump blood
throughout the body. In fact, cardiac muscle is only
found in the heart and makes up the bulk of the
heart's mass.
 Alpha receptors are the cell receptors that control
physiological processes like vasocontruction,intestinal
relaxation,pupil dilation upon interaction with
 There is tow types alpha 1 and alpha 2
 Methoxamine is an exemple of alpha 1 agonist
 while clonidine is an an example of a alpha 2
Alpha-1 agonists:
 agonists have been used primarily as pharmacological
reagents. They are currently used therapeutically
primarily as local vasoconstrictor agents. These are:
phenylephrine, methoxamine, midodrine
 They induce the effects of stimulation of alpha 1
adrenergic receptors. Administered intravenously,
they increase in blood pressure secondary to the
vasoconstrictor effect.
Alpha 2 receptors:
 Alpha 2 receptors in the brain stem and in the
periphery inhibit sympathetic activity and reduce
blood pressure. Alpha 2 receptor agonists such as
clonidine or guanabenz reduce central and peripheral
sympathetic overflow and via peripheral
presynaptic receptors may reduce peripheral
neurotransmitter release.
alpha2 agonist:
 The main alpha 2 agonist substance used in therapy
is clonidine
 It reduces blood pressure by reducing central
sympathetic tone and reduces heart rate by
simultaneous stimulation of para-sympathetic tone
 Stimulation of post-synaptic vascular alpha 2
adrenergic receptors potentially induces
vasoconstriction and increased blood pressure
Alpha1 blockers:
alpha2 blockers:
 Yohimbine
 Idozoxan
 Beta receptors are a group of receptors that control
vasodilation,relaxation of the bronchial and uterine
smooth muscles,and increase heart rate
The beta-adrenergic receptors beta 1 and 2 are
seven transmembrane receptors coupled to the
adenyl cyclase of a G protein. Their stimulation
induces the formation of cyclic AMP (from ATP),
second messenger. which activates protein kinase A
There is 3 types beta 1,beta 2 and beta3
Beta 1 and 2 agonists: isoprenaline, adrenaline
Beta 1 agonist: dobutamine, noradrenaline,
dopamine Preferential
beta 2 agonists: salbutamol, terbutaline, salmeterol
Beta 1 receptors:
 Beta 1 receptors are located in the heart. When Beta
1 receptors are stimulated they increase the heart rate
and increase the heart's strength of contraction or
its effects
 cardiac stimulant: inotropic, chronotropic,
dromotropic and positive bathmotropic effects
 Acceleration of cardiac relaxation
 ↑ lipolysis (stimulates the lipase of triglycerides)
 ↑ Secretion of renin by the juxta-glomerular apparatus
Beta 1-adrenergic agonists:
 Beta-adrenergic agonists such as isoprenaline,
dobutamine, noradrenaline and adrenaline are
substances with a primary amine function in their
structure, preventing practically any intestinal
resorption and passage of the blood-brain barrier.
The beta 2 receptors:
 The beta 2 receptors are located in the bronchioles of the lungs
and the arteries of the skeletal muscles
Cardiac stimulant (non-predominant but present receptors)
 ↑ release of Noradrenaline from sympathetic fibers Relaxation of
smooth fibers: vessels, bronchi, uterus, intestine.
 ↑ hepatic glycogenolysis
 ↑ hepatic neoglycogenesis
 ↑ muscle glycogenolysis
 ↑ insulin (low)
 ↓ serum potassium by stimulation of an NA + / K + pump
 ↑ tremor extremities (mechanism discussed, central or
peripheral origin)
The beta 2 agonist:
 The beta 2 agonist substances can be administered
orally because resorbed by the digestive tract. Their
elimination half-life may be longer, especially with
salmeterol (6 hours on average). They can also be
administered by air (aerosols) .This route of
administration particularly used during the treatment
of asthma allows for some of them (salbutamol,
terbutaline) an immediate and prolonged action and
reduces the amount of agonist passing into the
systemic circulation
beta blockers:
 beta blockers, are medications that reduce your
blood pressure. it work by blocking the effects of the
adrenaline. When you take beta blockers, your heart
beats more slowly and with less force, thereby
reducing blood pressure.
 They antagonize the effect of the stimulation of either
of the two types of beta 1 and 2 adrenergic
receptors, or preferentially beta 1 adrenergic receptors
(so-called cardi-selective beta-blockers).
difference between alpha and
beta receptors:
 Alpha receptors are
mostly involved in the
stimulation of effector
cells and constriction
of blood vessels. On the
other hand, beta
receptors are mostly
involved in
the relaxation of
effector cells and
dilatation of blood