ador, veiga - 2001 - activity metabolism in the lizard sceloporus occidentalis

7/23/2019 Ador, Veiga - 2001 - Activity Metabolism in the Lizard Sceloporus Occidentalis

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ACTIVITY METABOLISM IN THE LIZARD

SCELOPORUS OCCIDENTALIS

A L B E R T F. B E N N E T T A N D T O D D T . G L EE SO N

Schoo l of B iological Sciences, Un ivers ity of Ca liforn ia, Irv ine, Californ

Accepted 12/17/75)

Stan dard levels of oxygen consu mp tion an d oxygen consum ption an

duction during and after burst activity were measured in the iguanid

p us

occidentalis. T h e activ ity cap acity of this animal is restricted; it s

ous movem ent for only 1-2 min. Th e contribution of aerobic metabolis

tivity is strongly therm ally dep end ent. Maximal levels of oxygen con

achieved during activity at

3 0 4 0

C .

At lower temperatures, significant

oxygen up take , which app ear t o result from restricted ventilation. T

aerobic increase above resting levels occurs a t 5C, preferred body tem p

species. Repa ym ent of th e initial stages of oxygen d eb t is also mo st r

Lactic acid concentration reaches high levels during activity, and its

g r ea te st a t

30 C.

Anaerobic metabolism represents

62 -82y0

of th e e

during bu rst activ ity, accounting for nearly all of th e carb oh yd rate ca


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LBERT

F ENNETT ND

TODD T

GLEESON

accumulated lactate, and the capacity

for further activity is strongly curtailed

during the recovery period. These

generalizations also pertain to th e ac tivity

metabolism of many other reptilian

groups, b u t not to all Bartholomew an d

Tu cke r 1964; B en ne tt 1973b).

Certain methodological difficulties

hav e hampered th e examination of to ta l

energy metabolism, both anaerobic and

aerobic, during activity in the lower

vertebrates. Anaerobic energy produc-

tion can be estimated by the lactic acid

concentration in whole-body homoge-

nates, a procedure which avoids the

during and after stim

activity. These intervals

to permit a n accurate

con tributio n of aerobi

In addition, they can y

on th e therm al depende

eratio n of oxygen con

activity and of maxima

Sceloporus occidenta

fence lizard, is one of t

reptiles in southern C ali

in a gre at variety o

animals are territorial a

during the day on an

site of o ld lumber or


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CTIVITYMET BOLISM IN

LIZ RD

moths (Galleria sp.) and had access to

water a d libitum. Th e animals remained

healthy and active and were generally

held in captivity for less than 1 wk.

Animals were fasted for a t least 2 days

before experimentation.

In the experiments which determined

oxygen consumption and lac tate produc-

tion simultaneously during activity, a

single animal was weighed and measured.

Electrical leads were implanted

in

the

base of its tail. T h e lizard w as then

placed in a rectangular Lucite metabo-

lism cham ber (volume 534 cm3)

equipped with ports for air flow and

decrem ent was used to d

consumption according

Depocas and H a rt (195

The environmental

opened and incurrent a

po rts were closed, isola

the airtight chamber.

stimulated to maxim

electrical shocks of lo

livered with a Harvar

the implanted leads.

chamber was hit a nd s

the animal, which respo

of rapid running. Stim

tinued for 5 min. Air s


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68

ALBERT F BENNETT

AND

TODD

T

GLEESON

analyzer (see Depocas and Hart 1957).

Oxygen consumption during each minute

interval of activity and recovery was

calculated according to the formula

where

V volume of chamber (cm3) volume

of animal (cma)

V, volume of gas sample removed from

chamber (cm3)

RH

relative humidity in the cham-

figure 1. The thermal d

function is complex.

consumption is very s

ture dependent (Qlo

and 35 C but is essent

independent at 20-25 C

Such zones of therma

oxygen consumption

viously observed in o

Bennett and Dawson

nounced decrement i

consumption occurred

ning: the average eveni

below that in the af

decrease is not signific


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ACTIVITY METABOLISM

IN

A

LIZ RD

stimulation are reported in figure 2. The Qlo 30-35 C = 2.2, Q

total amount of oxygen consumed during

In addition to the gre

the period of stimulation increases with

consumption the rate

increasing temperature up to

35

C :

consumption increase

Qlo 20-25 C

=

2.9 Qlo 25-30 C

1.4

levels is also temperatu

ce lo ~o ru s occidental is


6/12

70

LBERT F.

BENNETT

AND TODD T. GLEESON

20

C, maximal levels are not attained consumption are coinc

until after the cessation of activity and activity burst at

30-40

stimulation. As body temperature in- acceleration of oxygen c

creases, the rate a t which maximal rates ing the first minute of

of oxygen consumption are achieved also great between 20 and 2

increases until maximal levels of oxygen Ventilation during burs

TABLE

THE EROBIC I N C R E M E N T D U R I N G 2 M I N

OF

BURST ACTIVITY AND

SCOPE (MAXIMAL

MINUTE

AEROBI C

I N C R E M E N T )

IN

SCELOPO

OCCIDENTALIS

TIMULATED FOR MIN

AEROBIC

SCOPE

AEROBIC

I N C R E ~ N T

Time

TEW. URING ACTIVITY tion

( C) N

(cma

O d k hl) (cmr OdIg hl


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ACTIVITY M ETABOLISM I N A LIZARD

TABLE

INCREMENTS ABOVE PRESTIMULATION

LEVELS

DURING MI

STIMULATION AND

MIN

OF RE OVERY I N

L ' S ~ ~ ~ ~CCIDENTALIS

Inc r emen t Increment

during during Change in

Temp.

St imu la t ion

Recovery

Inc re me nt R e c o v e 0

( C)

( c m J

O r l k h l ) cma

O z l k h l ) ( c m a

O r l k h l )

Nore.-Values shown are means of 5-8 animals.

stricted at low body temperature: no

costal movements are evident during

Lactate formation

the bout of bu rst a


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7

ALBERT

P BENNETT

AND TODD T. GLEESON

blood most rapidly at 35

C

All of these

iguanids have preferred thermal levels

of 35-38 C The interrelationships of

oxygen debt, lactate elimination, and

recovery in reptiles have not been

examined, however, and it would be

premature to speculate about their

interdependence or physiological signifi-

cance.

2 5

The delay at low b

in achieving maximal

consumption is not

pected, considering the

logical systems involve

port. A similar lag ha

reported for the marin

rhynchus crist tus Be

The low oxygen con

Sc eloporu s occidental s


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ACTIVITY XETABOLISM IN A

LIZ RD

TABLE

3

WHOLE-BODY LACTATE CONCENTRATIONS

OF

SCELOPORUS

OCCIDENTALIS BEFORE DUR-

ING,

AND

AFTER SPECIFIED

PERIODS OF

AC-

TIVITY

AT

35 C

Lactate Concen tra t ion

Condition IV h s s

w t )

Unstimulated. 4 0.40+0.04

min active..

4

1.34+0.16

2

min active.

4

1.73 0.10

5 min active. .

4

1.70_+0.25

5 min active+

5 min recovery. 6 1.82f 0.08

NOTE.-Valueshown are means+SE.

temperatures in active Scelopmus is not,

examining aerobic wo

aerobic increment duri

The thermal depend

activity metabolism in

more complex than wa

posed. A low temper

over a wide range of b

was postulated on the

tions on whole-body

(Bennett and Licht 19

lactate concentrations

Bennett et al. 1975). T

of whole-body lactat

narrow thermal increm

and Dipsosaurus (Ben


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c e l o ~ o r u soccidentalis


11/12

ACTIVITY METABOLISM I N LIZARD

hydrate catabolized enters anaerobic

pathw ays see Be nn ett e t al. 1975).

Energetic ou tpu t during burst ac tivity

is maximal over th e range of 30-35 C in

S.

occiderttalis. Body temperature of

animals in the field appears to have

some seasonal lability over this range

McGinnis 1966). Groups of anim als

caugh t in th e field during spring through

fall have mean body temperatures of

34.3-35.9 C. A similar group of winte r-

active animals, however, had a mean

body temperature of 30.4 C. All groups

tested in the laboratory had preferred

Sceloporus, in spite

Dipsosaurus is 2-3

Maximal anaerobic en

almost identical in the

production occurring a

rus and 40 C in D

output is maximized

modes at preferred b

40 C, in Dipsosaur

output is consequent

species 52 vs. 40 pmo

this increment is as

sup po rt of m uscular a

locom otory efficiency


12/12

76

ALBERT

F BENNETT A N D TODD T

GLEESON

D A W S O N .

R .

1975. On the physiological signifi- cidentalis. Comp. Biochem

cance of the preferred body temperatures of rep-

FR Y F.

E

J 1947. Effects

tiles. Pages 443-473

i n

D. M. GATES nd R.

B

animal activity. pu b. O

SCHMERLds. Perspectives in biophysical ecol-

8:1-62.

ogy. Springer-Verlag New York.

D A W S O NW.

R.

and G. A. BARTHOLOMEW.956.

Relatio n of oxygen cons um ption to body weight

temperature and temp erature acclimation in

lizards

Uta slansburiana

and

Sceloporus occi-

dentalis. Physiol. 2001. 29:40-51.

DEWCAS.F.. and T S HART.1957. Use of th e Pau l-

M c G r N ~ r s N 1966. Scel

ferred bod y temp era ture

lizard. Science 152 : 1090

IMOBERLY . R. 1968a. The

the common iguana

Igu

under restraint. Comp.

ing oxygen analy zer for measu remen t of oxygen

consum ption of an imals in open-circuit system s

19686. T h e metab ol

and in a short-lag closed circuit apparatus

mon iguana Igztana igzc

J

Appl. Physiol. 10:388-392.

ing. Com p. Biochem. Ph

FRANCIS . and G. R . BROOKS.970. Oxygen con-

WILSON

K. J

1974. T h e

sump tion rat e of heart beat and ventilatory

supply for act ivi ty to bo

rate of parietalectomized lizards

Sceloporzrs oc-

species of lizards. Copei

ador, veiga - 2001 - activity metabolism in the lizard sceloporus occidentalis

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