PMID- 1890648
OWN - NLM
STAT- MEDLINE
DCOM- 19911015
LR  - 20190510
IS  - 0022-3751 (Print)
IS  - 1469-7793 (Electronic)
IS  - 0022-3751 (Linking)
VI  - 437
DP  - 1991 Jun
TI  - GTP and noradrenaline-induced force in isolated toxin-permeabilized rat 
      anococcygeus and guinea-pig portal vein.
PG  - 543-61
AB  - 1. Strips of smooth muscle from rat anococcygeus and guinea-pig portal vein were 
      treated with solutions containing crude alpha-toxin from the bacterium 
      Staphylococcus aureus. This rendered the surface membrane permeable to small 
      molecular weight substances, but left functional sarcolemmal adrenoceptors. 
      Tension measurements from these preparations were used to investigate the effects 
      of guanosine-5'-triphosphate (GTP) on the noradrenaline-induced Ca2+ release from 
      the sarcoplasmic reticulum (SR) of the smooth muscle of rat anococcygeus and 
      guinea-pig portal vein. 2. Under conditions of low Ca2+ buffering (0.2 mM-EGTA), 
      applying a maximal dose of noradrenaline (30 microM) to a toxin-permeabilized 
      strip of anococcygeus muscle and longitudinal muscle of guinea-pig portal vein 
      caused a transient contracture. Subsequent exposures to noradrenaline resulted in 
      progressively smaller contractures. However, the rate of decline in the size of 
      the noradrenaline-induced contracture was greater in rat anococcygeus muscle than 
      in guinea-pig portal vein preparations. The decline in the size of the 
      contracture in toxin-permeabilized anococcygeus muscle was not due to a fall in 
      the Ca2+ content of the SR or a reduced Ca2+ release from the SR in response to 
      myo-inositol 1,4,5-trisphosphate (IP3). 3. The tension transients due to 
      noradrenaline were enhanced and maintained in the presence of 100 microM-GTP in 
      toxin-permeabilized guinea-pig portal vein. Addition of 100 microM-GTP caused a 
      transient contracture in permeabilized rat anococcygeus muscle and only promoted 
      the next noradrenaline response, thereafter the amplitude of the contractures 
      decayed to zero. 4. Addition of guanosine-5'-O-(2 thiodiphosphate) (GDP-beta-S, 
      100 microM) would be expected to cause a reversible reduction of the 
      noradrenaline response by binding to the intermediary G-protein. This was 
      observed in toxin-permeabilized portal vein, but in rat anococcygeus muscle, 
      GDP-beta-S caused slowing of the response to noradrenaline, thereafter the 
      response to noradrenaline was absent. The noradrenaline response did not recover 
      when GDP-beta-S was removed. 5. The non-metabolizable form of GTP, 
      guanosine-5'-O-(3-thiotriphosphate) (GTP-gamma-S, 100 microM), caused a transient 
      contracture in both toxin-permeabilized rat anococcygeus muscle and guinea-pig 
      portal vein. In both these tissues, the addition of GTP-gamma-S resulted in the 
      irreversible inhibition of the response to noradrenaline. 6. In the presence of a 
      high concentration (10 mM) of the Ca2+ buffer EGTA, GTP (100 microM) and 
      noradrenaline (30 microM) increased Ca(2+)-activated force in both 
      tissues.(ABSTRACT TRUNCATED AT 400 WORDS)
FAU - Crichton, C A
AU  - Crichton CA
AD  - Institute of Physiology, University of Glasgow.
FAU - Smith, G L
AU  - Smith GL
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - England
TA  - J Physiol
JT  - The Journal of physiology
JID - 0266262
RN  - 0 (Bacterial Toxins)
RN  - 0 (Hemolysin Proteins)
RN  - 0 (staphylococcal alpha-toxin)
RN  - 3G6A5W338E (Caffeine)
RN  - 85166-31-0 (Inositol 1,4,5-Trisphosphate)
RN  - 86-01-1 (Guanosine Triphosphate)
RN  - SY7Q814VUP (Calcium)
RN  - X4W3ENH1CV (Norepinephrine)
SB  - IM
MH  - Animals
MH  - Bacterial Toxins/pharmacology
MH  - Caffeine/pharmacology
MH  - Calcium/physiology
MH  - Cell Membrane Permeability/physiology
MH  - Guanosine Triphosphate/*physiology
MH  - Guinea Pigs
MH  - Hemolysin Proteins/pharmacology
MH  - Inositol 1,4,5-Trisphosphate/pharmacology
MH  - Muscle Contraction/*physiology
MH  - Muscle, Smooth/drug effects/*physiology
MH  - Muscle, Smooth, Vascular/physiology
MH  - Norepinephrine/*physiology
MH  - Rats
MH  - Rats, Inbred Strains
PMC - PMC1180062
EDAT- 1991/06/01 00:00
MHDA- 1991/06/01 00:01
PMCR- 1991/06/01
CRDT- 1991/06/01 00:00
PHST- 1991/06/01 00:00 [pubmed]
PHST- 1991/06/01 00:01 [medline]
PHST- 1991/06/01 00:00 [entrez]
PHST- 1991/06/01 00:00 [pmc-release]
AID - 10.1113/jphysiol.1991.sp018610 [doi]
PST - ppublish
SO  - J Physiol. 1991 Jun;437:543-61. doi: 10.1113/jphysiol.1991.sp018610.