The FDA first approved Invokana as the first SGLT2 drug in March 2013. Since then, it has become a cash cow for J&J and its Janssen Pharmaceuticals unit. In the first quarter of 2015, the drug already brought in $278 million, triple what it made last year.
During contraction, the smooth-muscle cell's intermediate filaments help to draw the cell up, like closing a drawstring purse. Calcium ions regulate contraction in smooth muscle, but they do it in a slightly different way than in skeletal muscle: 1  Calcium ions come from outside of the cell.2  Calcium ions bind to an enzyme complex on myosin, called calmodulin-myosin light chain kinase. Calcium ions come from outside of the cell. 2  Calcium ions bind to an enzyme complex on myosin, called calmodulin-myosin light chain kinase. 3  The enzyme complex breaks up ATP into ADP and transfers the P i directly to myosin. 4  This P i transfer activates myosin.
1 Thin filaments in smooth muscle do not contain troponin. 2  calcium does not bind to troponin but, rather, to a protein called calmodulin. 3  The calcium-calmodulin complex 'activates' myosin which then binds to actin & contraction (swivelling of cross-bridges) begins.he cell membrane of a muscle cell is called the sarcolemma, and this membrane, like that of neurons, maintains a membrane potential. So, impulses travel along muscle cell membranes just as they do along nerve cell membranes. However, the 'function' of impulses in muscle cells is to bring about contraction.