AbstractPrecise signaling at the neuromuscular junction (NMJ) is essential for proper muscle contraction. In theC. eleganspharynx, acetylcholine (ACh) released from the MC and M4 motor neurons stimulates two different types of contractions in adjacent muscle cells, termed pumping and isthmus peristalsis. MC stimulates rapid pumping through the nicotinic ACh receptor EAT-2, which is tightly localized at the MC NMJ, andeat-2mutants exhibit a slow pump rate. Surprisingly, we found thateat-2mutants also hyperstimulated peristaltic contractions, and these are characterized by increased and prolonged Ca2+transients in the isthmus muscles. This hyperstimulation depends on crosstalk with the GAR-3 muscarinic acetylcholine receptor asgar-3mutation specifically suppressed the prolonged contraction and increased Ca2+observed ineat-2mutant peristalses. Similar GAR-3 dependent hyperstimulation was also observed in mutants lacking theace-3acetylcholinesterase, and we suggest that NMJ defects ineat-2andace-3mutants result in ACh stimulation of extrasynaptic GAR-3 receptors in isthmus muscles.gar-3mutation also suppressed slow larval growth and prolonged lifespan phenotypes that result from dietary restriction ineat-2mutants, indicating that crosstalk with the GAR-3 receptor has a long-term impact on feeding behavior andeat-2mutant phenotypes.Article SummaryAcetylcholine stimulates different contractions in adjacent muscle cells in theC. eleganspharynx called pumping and peristalsis. The signaling mechanisms stimulating pumping have been characterized, but how these mechanisms affect peristalsis is unknown. Here we examined muscle contractions and Ca2+transients during peristalsis in wild-type animals and acetylcholine signaling mutants. Surprisingly we found that while mutants affecting theeat-2nicotinic acetylcholine receptor exhibited reduced pumping, they also hyperstimulated peristalses. This hyperstimulation depends on crosstalk with the GAR-3 muscarinic acetylcholine receptor in adjacent cells, and it contributes to the well-characterized dietary restriction and extended adult lifespan observed ineat-2mutants.