i hate the stuff (search my posts) I have used albuterol for asthma (pills and inhaler) off and on since i was a kid----while clen is billed as long acting albuterol (half life of 4 vs. 36 hours) it made me shake and send my HR through the roof--at 20 mcg of pharm grade. never touched it again.
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'The Effects of Clenbuterol on Skeletal and Cardiac Muscle of Rats when Combined with Aerobic and Anaerobic Exercise, ' Biochemistry of Exercise Ninth International Conference Abstracts, #117, p 75, 1994
clenbuterol also yielded three very negative changes. First, after just four weeks, clenbuterol-treated rats were unable to maintain their normal swimming or running training intensities, while clean rodents were quite capable of continuing. Secondly, the hearts of the clenbuterol-taking, trained rats increased dramatically in size compared to the hearts of sedentary rats, but the heart expansion was probably due to the infiltration of collagen fibres into the heart walls, not an increase in heart-muscle cells. Collagen is a tough connective tissue which doesn't augment heart-muscle power but in fact stiffens the heart, potentially leading to a decrease in cardiac output. Increases in collagen may also produce cardiac arrhythmias. Thirdly, clenbuterol rats suffered from noticeable cardiac-cell degeneration.