PMID- 1614828
OWN - NLM
STAT- MEDLINE
DCOM- 19920729
LR  - 20190726
IS  - 0031-6768 (Print)
IS  - 0031-6768 (Linking)
VI  - 420
IP  - 5-6
DP  - 1992 Apr
TI  - Endogenous and exogenous agonist-induced changes in the coupling between [Ca2+]i 
      and force in rat resistance arteries.
PG  - 536-43
AB  - The relationship between isometric tension and free cytoplasmic calcium, [Ca2+]i, 
      was investigated in rat isolated resistance arteries using fura-2. Depolarisation 
      with 125 mM K+ induced a tonic contraction, while [Ca2+]i increased transiently 
      but stabilised above resting [Ca2+]i. Furthermore, the tension/[Ca2+]i ratio was 
      lower during activation with 125 mM K+ if the effect of endogenous noradrenaline 
      (NA) was inhibited. Concentration/response curves with NA and K+ indicated that 
      NA increased the sensitivity to [Ca2+]i. Calcium concentration/response curves in 
      the presence of 10 microM NA or 125 mM K+ showed that NA could induce force at or 
      below resting [Ca2+]i, while for any given bath calcium concentration, [Ca2+]i 
      was similar in the presence of NA or K+. Addition of NA or vasopressin (AVP) to 
      vessels depolarised with 125 mM K+ caused force development but no increase in 
      [Ca2+]i, suggesting that agonists increase the efficacy of [Ca2+]i. However, 
      during activation with AVP the efficacy of [Ca2+]i decreased time-dependently. 
      The results suggest that in resistance arteries [Ca2+]i plays a crucial role in 
      excitation-contraction coupling, but the tension/[Ca2+]i relationship can be 
      modified by exogenous and endogenous agonists.
FAU - Jensen, P E
AU  - Jensen PE
AD  - Institute of Pharmacology, University of Aarhus, Denmark.
FAU - Mulvany, M J
AU  - Mulvany MJ
FAU - Aalkjaer, C
AU  - Aalkjaer C
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - Germany
TA  - Pflugers Arch
JT  - Pflugers Archiv : European journal of physiology
JID - 0154720
RN  - 113-79-1 (Arginine Vasopressin)
RN  - 9NEZ333N27 (Sodium)
RN  - RWP5GA015D (Potassium)
RN  - SY7Q814VUP (Calcium)
RN  - X4W3ENH1CV (Norepinephrine)
SB  - IM
MH  - Animals
MH  - Arginine Vasopressin/pharmacology
MH  - Biomechanical Phenomena
MH  - Calcium/*metabolism/pharmacology
MH  - *Muscle Contraction
MH  - Muscle, Smooth, Vascular/*metabolism
MH  - Norepinephrine/pharmacology
MH  - Potassium/pharmacology
MH  - Rats
MH  - Rats, Inbred Strains
MH  - Sodium/pharmacology
MH  - Vascular Resistance
EDAT- 1992/04/01 00:00
MHDA- 1992/04/01 00:01
CRDT- 1992/04/01 00:00
PHST- 1992/04/01 00:00 [pubmed]
PHST- 1992/04/01 00:01 [medline]
PHST- 1992/04/01 00:00 [entrez]
AID - 10.1007/BF00374630 [doi]
PST - ppublish
SO  - Pflugers Arch. 1992 Apr;420(5-6):536-43. doi: 10.1007/BF00374630.