PMID- 9420852
OWN - NLM
STAT- MEDLINE
DCOM- 19980122
LR  - 20191102
IS  - 1071-5576 (Print)
IS  - 1071-5576 (Linking)
VI  - 2
IP  - 3
DP  - 1995 May-Jun
TI  - Decreased response to vasopressin in the mesenteric resistance arteries of 
      pregnant rats: effects of nifedipine and Bay K 8644.
PG  - 516-22
AB  - OBJECTIVE: The purpose of this study was to investigate the contribution of 
      potential-operated calcium (POC) channels in the mechanisms of the blunted 
      effects of vasoconstrictors on mesenteric resistance arteries during normal 
      pregnancy. METHODS: Mesenteric resistance arteries of virgin and term pregnant 
      rats were set up under optimum passive tension in wire myograph systems. 
      Cumulative concentration-response curves of arginine8-vasopressin (AVP) were 
      measured in the absence and presence of nifedipine or Bay K 8644, a blocker and 
      an activator, respectively, of POC channels. Binding studies were performed on 
      membrane preparations of the mesenteric vascular bed of both groups of rats using 
      saturation with [3H]nitrendipine. RESULTS: The maximal response to AVP was 
      statistically similar in the two groups of arteries. Pregnancy shifted the AVP 
      concentration-response curves to the right. Nifedipine (1 mumol/L) similarly 
      reduced the maximum response to AVP in arteries of both groups, but produced a 
      larger increase in EC50, the concentration inducing 50% maximum response, in 
      resistance arteries of virgin versus pregnant rats. Bay K 8644 did not affect the 
      maximum tension reached with AVP. However, it increased the effects of small 
      concentrations of AVP in arteries of both groups. This was more important in 
      tissues of virgin than pregnant rats. Binding of [3H]nitrendipine to membrane 
      preparations of mesenteric vessels was not modified by pregnancy. CONCLUSION: Our 
      results suggest a reduced functional influence of POC channels in the myotropic 
      effects of AVP on mesenteric resistance arteries in pregnancy. This decreased 
      influence of POC channels may contribute to resistance of the vasculature to 
      vasopressor agents during pregnancy.
FAU - St-Louis, J
AU  - St-Louis J
AD  - Laboratoire de Pharmacologie Vasculaire Perinatale, Hopital Ste-Justine, 
      Montreal, Quebec, Canada.
FAU - Pare, H
AU  - Pare H
FAU - Roy, B
AU  - Roy B
FAU - Brochu, M
AU  - Brochu M
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - United States
TA  - J Soc Gynecol Investig
JT  - Journal of the Society for Gynecologic Investigation
JID - 9433806
RN  - 0 (Calcium Channels)
RN  - 113-79-1 (Arginine Vasopressin)
RN  - 71145-03-4 (3-Pyridinecarboxylic acid, 
      1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester)
RN  - 9B627AW319 (Nitrendipine)
RN  - I9ZF7L6G2L (Nifedipine)
RN  - X4W3ENH1CV (Norepinephrine)
SB  - IM
MH  - 3-Pyridinecarboxylic acid, 
      1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl 
      ester/*pharmacology
MH  - Animals
MH  - Arginine Vasopressin/*pharmacology
MH  - Calcium Channels/physiology
MH  - Cell Membrane/metabolism
MH  - Dose-Response Relationship, Drug
MH  - Female
MH  - In Vitro Techniques
MH  - Mesenteric Arteries/drug effects/*physiology
MH  - Muscle Contraction/drug effects
MH  - Muscle, Smooth, Vascular/drug effects/*physiology
MH  - Nifedipine/*pharmacology
MH  - Nitrendipine/metabolism
MH  - Norepinephrine/pharmacology
MH  - Pregnancy
MH  - Pregnancy, Animal/*physiology
MH  - Rats
MH  - Rats, Sprague-Dawley
MH  - Reference Values
MH  - Vascular Resistance/drug effects
EDAT- 1995/05/01 00:00
MHDA- 1998/01/08 00:01
CRDT- 1995/05/01 00:00
PHST- 1995/05/01 00:00 [pubmed]
PHST- 1998/01/08 00:01 [medline]
PHST- 1995/05/01 00:00 [entrez]
AID - 107155769400059A [pii]
AID - 10.1016/1071-5576(94)00059-a [doi]
PST - ppublish
SO  - J Soc Gynecol Investig. 1995 May-Jun;2(3):516-22. doi: 
      10.1016/1071-5576(94)00059-a.