something big cat from bodybuilding.com wrote , very informative :
"Testosterone commences by increasing calcium influx in the SR in muscles. Since calcium release is required for the cross-bridging of myofibrils this increases contractile potential in the muscle. Muscle contraction leads to two things : release of arachidonic acid from intramuscular fat and the upregulation of GLUT4 independent of insulin. Since both are increased by testosterone, these have just been facilitated.
At the same time creatine flow is improved. Creatine improves multiplication through division of sattelite cells in muscle. Testosterone converts to estradiol which increases again the ability of GLUT4, but then dependent of insulin. It also increases outflow of GH, which stimulates release of IGF-1 in the muscle. IGF-1 then makes the sattelite cells donate nuclei to the damaged muscle tissue. This creates more androgen receptors per fiber, so as to speed recovery. More AR however also means increased growth potential and more room for testosterone to exert its actions on protein synthesis. Testosterone binds to the AR and would normally have a relative loose binding, but since arachidonic acid when free is turned into prostaglandins like PGF2a, these will in turn stabilize the binding, increasing and prolonging the genetic transcription. Testosterone expresses similar fashions of genetic transcription as all steroids, safe for winstrol, which appears to be unique. But in several testosteron's transcription was nominally higher.
Story doesn't even end there. Testosterone antagonizes the cortisol receptor, again leading to a positive nitrogen balance and less muscle breakdown. It converts to DHT, which increases neural response, strength and uptake of nutrients in muscle. And it upgrades beta adrenoreceptors again leading to increased second messenger protein synthesis and a greater release of fatty acids from adipose tissue that can be used as fuel. Lastly because of the massive increases in both insulin dependent and independent GLUT4 it allows for massive influx and overcompensation of glucose, amino acids for transcription and creatine. So first of all providing the building blocks for anabolism and secondly due to increased glycogen and creatine in the muscle, cell volume increases. And cell volume is again a direct signal for increased protein synthesis. “
.gif "IP Gear")
