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114 Cardio Diabetes Medicine 2017
Rho/Rhokinase, prostaglandin-E and proteocyclin.
Sexual Stimulation
Cavernosal smooth muscle cells in the penis are
predominately found in the contracted state with Central and
minimal blood flowing through the cavernous si-
nuses. The balance between known contractile sys- Peripheral
tems (RhoA/Rho-kinase, α-adrenergic, endothelin, Initiation or erection Activation of nNOS-
angiotensin, thromboxane A ) and vasodilatory sec- Derived NO
2
ond-messenger systems (adenylate cyclase-cyclic
AMP and guanylate cyclase-cyclic GMP) determines Cavernosal smooth
the overall tone of corpora cavernosa smooth muscle
of the penis This balance is controlled by both central Muscle Relaxation
and peripheral mechanisms and involves a plethora Blood Flow -
of neurotransmitters acting through various signal Mediated Shear
transduction pathways. Stress
Of all the mediators of the endothelium the most im-
6
portant is Nitric oxide . Nitric oxide is the main chem- Cavernosal P13
ical currency which initiates the erectogenic process. Kinase / Akt
It’s the only free radical which is anti thrombogenic
and anti atherogenic and the only biological mole- Maintenance of Activation
cule which out completes superoxide dismutase for erection
superoxide. Its protective action includes Smooth Phophorylation of
muscle relaxation and vasodilatation, Essential for eNOS
regulation of blood pressure,
Reduces proliferation of vascular smooth muscle Endothelial - Derived
and Protects blood vessel intima from injurious con- NO
sequences of platelet aggregation. Thus in endothe-
lial dysfunction we see reduction in NO and this NO
deficiency promotes Inflammation, Oxidation of lipo- Maximal Erection
proteins, Smooth muscle proliferation, Accumulation
of lipid rich material, Platelet activation and thrombus
formation
In patients with Metabolic syndrome, ageing and
neurological disorders which are the organic causes
of Erectile dysfunction the main chemical currency
Nitric oxide is reduced which is the prime molecule
to initiate the erectogenic mechanism and also di-
minished cyclic GMP bio availability.
Pic: An “Airport hub” model of endothelial functions. In this mod-
el, all functions are intrinsically interconnected, and any impair-
ment of one would be affect the others. Some essecntial mediators
fo these functions are shown in brackerts. Pathophysiological con-
sequences of endothelial dysfunction are depicted at the primeter,
HTN, hypertension, EDHF, endothelium - derived hyperpolarizing
factor; EDF, endohtelium - derived relaxign factor, NO, nitric oxide;
VSM vascular smothe muscle; PAI-1, plasminogen activator inhibi-
tor-1; TF, tissue factor, PA, plasminogen actovator; MCP, monocyte
chemotactic protein; prot protein
Adapted from Hurt et al 2002 9
GCDC 2017
