passages.id: split_4_test_1212_passage
passages.type: progene_text
passages.text: The agonist - specific desensitization of the M(1) Ach and somatostatin receptors was significantly attenuated in antisense - expressing cells , whereas desensitization of P2y(1) and P2y(2) purinergic and AT1 angiotensin receptors was unaffected by reduced arrestin levels .