Act 1, Scene 1 is the first time we see Antonio and Bassanio interact, and in this scene we also see several literary devices that show us they are very good friends.
Antonio's first words are to ask,
Well, tell me now what lady is the same / To whom you swore a secret pilgrimage, / That to-day you promised to tell me of.
From this we see that Antonio and Bassanio trust one another with their secrets, and that Antonio really cares to hear the latest news about his friend's life.
Bassanio does not immediately tell Antonio about the lady, because he has a large favor to ask of Antonio, and he wants to make sure that he is free to ask it. Antonio assures him:
... be assured / My purse, my person, my extremest means / Lie all unlocked to your occasions.
This is the literary device of foreshadowing. "My person" means "my body." Although Antonio could not possibly imagine it at this point in the play, his "person" will almost be "unlocked" (opened up) for the sake of Bassanio, when Shylock comes to take a pound of Antonio's flesh.
Even with this assurance, Bassanio remains uncomfortable asking Antonio for anything, because Antonio has already lent him money, which Bassanio has failed to repay. So in lines 140 - 153, Bassanio engages in a long metaphor. He talks about how, as a boy, if he lost one arrow, he would shoot a second arrow after it. Then going after the second arrow, he was often able to find the first. In the same way, he says, if Antonio will lend him money yet again, Bassanio is sure this loan will allow him to repay all his debts to Antonio, or at least the latter debt.
At this point, Antonio gets a little hurt that Bassanio is trying to motivate him with the hope of getting his money back; or, as he puts it, "to wind about my love with circumstance." Antonio thinks his love for Bassanio should be motivation enough. It should not have to be re-enforced with other considerations, like wrapping additional string around an already sturdy rope or chain. This is a beautiful metaphor.
Antonio adds that Bassanio is doing him a wrong "In making question of my uttermost." Here, for those who know how the play will go, there is more chilling foreshadowing. At this point neither man can imagine how far to the "uttermost" Antonio will have to go for the sake of his loyalty to Bassanio.