Question 44

[asfino12217]

If Hypothesis B is correct, which of the following results could be predicted?


a.) Ibogaine would have nearly an immediate effect.[x]
b.) Ibogaine would result in the loss of neural transmission over time.[x]
c.) The effect of ibogaine would be independent of the amount of cocaine in the synaptic cleft.[x]
d.) The number of dopamine transporters would increase.[x]

why couldn't the answer be c?

[jellywing_2058]

If there was more cocaine, the ibogaine quantities would be insufficient in order to take effect. Therefore, the activity of ibogaine is dependent on the amount of cocaine present, making answer choice C wrong.

[jsfkt78927]

Cocaine binds the atp-dependent transporter in a noncompetitive fashion, ie its binding cannot be overcome by the [dopamine]. if it didnt bind in this fashion then some dopamine, however small would be brought back into the cell.

Similarly, ibogaine seems to act in the same fashion. It binds to the transporter, and as the passage says, ' it does not allow cocaine to bind the transporter.' In addition to this, if it bound the transporter competitively then it would bind its active site, preventing what ever interactions that happen between dopamine and the transporter, (or you may imagine that it binds the atp-dependent-domain, and in this sense dopamine would still not be taken in b/c atp could not be hydrolyzed). These two pieces of infomatino would make someone believe ibogaine is bound in a non-competitive fashion to the transporter.

What does this mean?

That the effect of ibogaine would be independent of the amount of cocain in the synaptic cleft.

You might say, 'its not an enzyme, wha wha wah.' It has enzymatic properties, chceck out the passage once more holmes, ill quote it for you '...addictive prop. of cocaine are purported to result, in part, from its binding the ATP-dependent dopamine transporter at the presynaptic...' So the transporter hydrolyzes atp for its metabolic functions.