226
GEORGE G. LATIES
tern, the rate of electron passage, in turn, will depend not only upon the
nature of the enzymes and coenzymes constituting the oxidative unit,
but also upon the prevalence and rate of regeneration of phosphate
acceptors. It would therefore not be inconsistent to find a response both
to substrate and to dinitrophenol in the same tissue, and such, in fact,
is frequently the case (see Eliasson and Mathiesen, 1956; Porter and
Runeckles, 1956).
1. Regulation in Intact Organs
By and large, except in the instances where starvation is purposely
brought about experimentally, fresh tissues exhibit a limited response, or
no response at all, to an exogenous addition of substrate. However, in a
great variety of tissues, and whether the tissues respond to substrate or
not, the addition of dinitrophenol or other uncouplers elicits an immediate and pronounced respiratory increment. A variety of experiments
involving dinitrophenol stimulation are presented in Table 1.
As already suggested in the previous section, in a system wherein the
level of phosphate acceptor limits the respiratory rate, any process which
would cause regeneration of the acceptor might be expected to stimulate
respiration. The onset of certain energy-requiring cellular processes accordingly results in an increase in respiration, the implication being that
the energy is supplied by the utilization of high-energy phosphate or its
equivalent, phosphate acceptors being created in the process. Thus it
has been found that the accumulation of salt against a concentration
gradient by a variety of tissues is accompanied by an increase in respiration (Lundegárdh, 1953a; Robertson and Turner, 1945); the metabolically
controlled absorption of water into disks of tubers (Hackett and Thimann, 1953; Hanson and Bonner, 1954) or tuberous roots results in a concomitant respiratory rise; and the growth in length of pea (Christiansen
and Thimann, 1950) and of Avena (Bonner, 1949) sections in response
to indoleacetic acid and other growth hormones is paralleled by an increment in the respiration. The most salient change in recent years with
respect to the manner in which the interrelationship of work and respiration rate is to be regarded, is that the respiratory increment is now
recognized to be a consequence of the work process and not the cause
of it. Fundamentally the distinction is without meaning, since the
energy utilized derives in fact from the increment in respiration. However, in terms of providing insight into the relation between cellular
work and respiratory rate, the new concept represents a valuable advance (Millerd and Bonner, 1953).
Many of the ostensibly conflicting reports respecting the respiratory
response of tissues to certain treatments may conceivably be reconciled
GEORGE G. LATIES
tern, the rate of electron passage, in turn, will depend not only upon the
nature of the enzymes and coenzymes constituting the oxidative unit,
but also upon the prevalence and rate of regeneration of phosphate
acceptors. It would therefore not be inconsistent to find a response both
to substrate and to dinitrophenol in the same tissue, and such, in fact,
is frequently the case (see Eliasson and Mathiesen, 1956; Porter and
Runeckles, 1956).
1. Regulation in Intact Organs
By and large, except in the instances where starvation is purposely
brought about experimentally, fresh tissues exhibit a limited response, or
no response at all, to an exogenous addition of substrate. However, in a
great variety of tissues, and whether the tissues respond to substrate or
not, the addition of dinitrophenol or other uncouplers elicits an immediate and pronounced respiratory increment. A variety of experiments
involving dinitrophenol stimulation are presented in Table 1.
As already suggested in the previous section, in a system wherein the
level of phosphate acceptor limits the respiratory rate, any process which
would cause regeneration of the acceptor might be expected to stimulate
respiration. The onset of certain energy-requiring cellular processes accordingly results in an increase in respiration, the implication being that
the energy is supplied by the utilization of high-energy phosphate or its
equivalent, phosphate acceptors being created in the process. Thus it
has been found that the accumulation of salt against a concentration
gradient by a variety of tissues is accompanied by an increase in respiration (Lundegárdh, 1953a; Robertson and Turner, 1945); the metabolically
controlled absorption of water into disks of tubers (Hackett and Thimann, 1953; Hanson and Bonner, 1954) or tuberous roots results in a concomitant respiratory rise; and the growth in length of pea (Christiansen
and Thimann, 1950) and of Avena (Bonner, 1949) sections in response
to indoleacetic acid and other growth hormones is paralleled by an increment in the respiration. The most salient change in recent years with
respect to the manner in which the interrelationship of work and respiration rate is to be regarded, is that the respiratory increment is now
recognized to be a consequence of the work process and not the cause
of it. Fundamentally the distinction is without meaning, since the
energy utilized derives in fact from the increment in respiration. However, in terms of providing insight into the relation between cellular
work and respiratory rate, the new concept represents a valuable advance (Millerd and Bonner, 1953).
Many of the ostensibly conflicting reports respecting the respiratory
response of tissues to certain treatments may conceivably be reconciled