three systems of regulation of cell calcium are suggested to be operative in the ureter muscle : a fast one which is highly temperature-dependent and responsible for the relaxation of the phasic contraction ( probably the sarcoplasmic reticulum ) , and two slow membrane-linked carriers , one of which is dependent on na0+ ( probably na-ca exchange ) and another one which is independent of na0+ and inhibited by la3+ ( probably ca-pump ) .
C0007634
cell
C0036226
sarcoplasmic reticulum