PMID- 7631849
OWN - NLM
STAT- MEDLINE
DCOM- 19950901
LR  - 20171213
IS  - 0002-9513 (Print)
IS  - 0002-9513 (Linking)
VI  - 269
IP  - 1 Pt 2
DP  - 1995 Jul
TI  - GTP requirement for isoproterenol activation of calcium channels in vascular 
      myocytes.
PG  - H195-202
AB  - The effects of activating the beta-adrenoceptor pathway on calcium current (ICa) 
      in rabbit portal vein (PV) were studied in myocytes freshly isolated by 
      collagenase and elastase treatment. ICa was measured at room temperature (20 
      degrees C) using whole cell, voltage-clamp methods from a holding potential of 
      -60 mV in cells dialyzed with a pipette solution containing (mM) 100 CsCl, 20 
      tetraethylammonium chloride, 5 NaCl, 5 MgATP, 20 
      N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (HEPES), and 10 
      1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA). The cells were 
      superfused with a solution containing (mM) 140 NaCl, 5 KCl, 1 MgCl2, 5 CaCl2, 10 
      HEPES, and 10 glucose. Only L-type ICa was present in these myocytes, averaging 
      3.5 +/- 0.3 pA/pF at +10 mV under control conditions. With 0.1 mM guanosine 
      5'-triphosphate (GTP) added to the pipette solution, 1 microM isoproterenol (Iso) 
      or forskolin (Fsk) uniformly increased ICa: Iso by 45 +/- 5% and Fsk by 88 +/- 
      11%. This augmentation of ICa was not associated with significant changes in the 
      voltage dependence of activation or inactivation but was associated with a small 
      increase in the rate of inactivation of ICa. Fsk was also associated with an 
      increased rate of ICa activation. The Iso effect was blocked by pretreatment with 
      1 microM propranolol and reversed by propranolol after Iso exposure. The ICa 
      response to 10 microM Iso or Fsk was smaller than the response to 1 microM, with 
      some cells showing a steady-state reduction in ICa. When the latter occurred, the 
      voltage dependence of availability was shifted to the left by 5 +/- 0.4 
      mV.(ABSTRACT TRUNCATED AT 250 WORDS)
FAU - Shi, Q Y
AU  - Shi QY
AD  - Bockus Research Institute, Graduate Hospital, University of Pennsylvania, 
      Philadelphia 19146, USA.
FAU - Cox, R H
AU  - Cox RH
LA  - eng
GR  - HL-28476/HL/NHLBI NIH HHS/United States
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - United States
TA  - Am J Physiol
JT  - The American journal of physiology
JID - 0370511
RN  - 0 (Calcium Channels)
RN  - 0 (Thionucleotides)
RN  - 146-91-8 (Guanosine Diphosphate)
RN  - 1F7A44V6OU (Colforsin)
RN  - 37589-80-3 (Guanosine 5'-O-(3-Thiotriphosphate))
RN  - 71376-97-1 (guanosine 5'-O-(2-thiodiphosphate))
RN  - 86-01-1 (Guanosine Triphosphate)
RN  - L628TT009W (Isoproterenol)
SB  - IM
MH  - Animals
MH  - Calcium Channels/*drug effects/physiology
MH  - Colforsin/pharmacology
MH  - Guanosine 5'-O-(3-Thiotriphosphate)/pharmacology
MH  - Guanosine Diphosphate/analogs & derivatives/pharmacology
MH  - Guanosine Triphosphate/*pharmacology
MH  - Isoproterenol/antagonists & inhibitors/*pharmacology
MH  - Male
MH  - Muscle, Smooth, Vascular/*metabolism
MH  - Patch-Clamp Techniques
MH  - Rabbits
MH  - Thionucleotides/pharmacology
EDAT- 1995/07/01 00:00
MHDA- 1995/07/01 00:01
CRDT- 1995/07/01 00:00
PHST- 1995/07/01 00:00 [pubmed]
PHST- 1995/07/01 00:01 [medline]
PHST- 1995/07/01 00:00 [entrez]
AID - 10.1152/ajpheart.1995.269.1.H195 [doi]
PST - ppublish
SO  - Am J Physiol. 1995 Jul;269(1 Pt 2):H195-202. doi: 
      10.1152/ajpheart.1995.269.1.H195.