Endotoxins in cholera and pertussis toxins interfere with in vivo responses to these agents in the albino rabbit Eye

Intravitreal injections of cholera or pertussis toxin (CTX or PTX, 0.5-1 μg/eye) decreased intraocular pressure (IOP) up to 50% in the albino rabbit eye, which lasted up to six days. Both toxins were active on G-proteins as determined by in vitro and in vivo effects on ciliary process adenylyl cyclase activity and by ADP ribosylation of G-protein αsubunits with ³²P-NAD. However, forty-two hours after toxin injection aqueous humor proteins increased from control levels of 0.8-1.2 nig/ml to 8-25 mg/ml. Both toxins contained 1-3 parts per thousand endotoxin sufficient to cause the IOP and aqueous humor protein responses observed. We conclude that the in vivo responses to intraocular CTX or PTX obtained from commercial sources may not provide unequivocal evidence for the role(s) of G-proteins in aqueous humor dynamics, and must be interpreted with caution.