Question

You are running some tests with your new experimental wrinkle reducing drug, called NoRaisin. When treating cultured muscle fibers in a dish with NoRaisin, you notice that your cells do not contract when stimulated by an alpha motoneuron; this is ultimately what will reduce wrinkles, so that’s good. Additional testing shows that even though action potentials are propagated down the entire sarcolemma, there is no rise in intracellular calcium as a result. So what is NoRaisin MOST LIKELY doing?

the drug stops the motor end plate from working properly

the drug stops the release of acetylcholine

the drug stops troponin from working properly

the drug stops DHP from working properly

Answer 1

D) the drug stops DHP from working properly

Explanation: DHP is the dihydropyridine receptor (DHPR), normally a voltage-dependent calcium channel. It functions in skeletal muscle essentially as a voltage sensor, triggering intracellular calcium release for excitation-contraction coupling.

The blockage of this receptor by NoRaisin prevents the intracellular release of calcium from sarcoplasmic reticulum. This prevents the contraction of the muscle that helps to prevent wrinkling.