The effect of chronic nitric oxide synthase inhibition on blood pressure and heart rate in unrestrained pregnant rats as recorded by radiotelemetry

Catalin S. Buhimschi, Remzi Gokdeniz, George Saade, Irina A. Buhimschi, Robert E. Garfield

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

OBJECTIVES: The objective of this study was to determine the effect of chronic nitric oxide synthase inhibition on heart rate and intravascular blood pressure in unrestrained pregnant rats as recorded by radiotelemetry. STUDY DESIGN: Heart rate and systolic and diastolic blood pressures were monitored beginning with day 6 of pregnancy and until 1 week post partum with a radiotelemetric device. On day 10 of pregnancy osmotic minipumps were implanted subcutaneously and loaded to continuously deliver N(G)-nitro-L- arginine methyl ester (50 mg/d per rat, n = 6 animals) or vehicle (control group, n = 6 animals). RESULTS: Blood pressure in the animals treated with N(G)-nitro-L-arginine methyl ester significantly increased compared with that in the control group and heart rate significantly decreased immediately after nitric oxide synthase blockade. Blood pressure then trended downward as gestation progressed, until the difference between the control group and the group treated with N(G)-nitro-L-arginine methyl ester became nonsignificant after day 17. Refractoriness to nitric oxide synthase blockade was especially evident in the diastolic pressure. Systolic, diastolic, and mean blood pressures in the rats treated with N(G)-nitro-L-arginine methyl ester were again significantly higher than those in the control group immediately after delivery and remained so despite a lower heart rate until the experiment was ended on postpartum day 6. CONCLUSIONS: Radiotelemetry can be used to monitor heart rate and intra-arterial blood pressure in unstressed, unrestrained animals. Chronic inhibition of nitric oxide does not cause sustained hypertension throughout pregnancy. Nitric oxide does not appear to be the only factor responsible for the vascular changes in pregnancy. The factors responsible for the refractoriness to nitric oxide synthase blockade are specific to pregnancy and disappear immediately after delivery.

Original languageEnglish (US)
Pages (from-to)159-164
Number of pages6
JournalAmerican Journal of Obstetrics and Gynecology
Volume181
Issue number1
DOIs
StatePublished - 1999
Externally publishedYes

Fingerprint

Nitric Oxide Synthase
Heart Rate
Blood Pressure
NG-Nitroarginine Methyl Ester
Pregnancy
Control Groups
Nitric Oxide
Postpartum Period
Arterial Pressure
Hypertension
Equipment and Supplies

Keywords

  • Gestation
  • Hypertension
  • N(G)-nitro-L-arginine methyl ester
  • Preeclampsia
  • Pregnancy

ASJC Scopus subject areas

  • Medicine(all)
  • Obstetrics and Gynecology

Cite this

The effect of chronic nitric oxide synthase inhibition on blood pressure and heart rate in unrestrained pregnant rats as recorded by radiotelemetry. / Buhimschi, Catalin S.; Gokdeniz, Remzi; Saade, George; Buhimschi, Irina A.; Garfield, Robert E.

In: American Journal of Obstetrics and Gynecology, Vol. 181, No. 1, 1999, p. 159-164.

Research output: Contribution to journalArticle

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abstract = "OBJECTIVES: The objective of this study was to determine the effect of chronic nitric oxide synthase inhibition on heart rate and intravascular blood pressure in unrestrained pregnant rats as recorded by radiotelemetry. STUDY DESIGN: Heart rate and systolic and diastolic blood pressures were monitored beginning with day 6 of pregnancy and until 1 week post partum with a radiotelemetric device. On day 10 of pregnancy osmotic minipumps were implanted subcutaneously and loaded to continuously deliver N(G)-nitro-L- arginine methyl ester (50 mg/d per rat, n = 6 animals) or vehicle (control group, n = 6 animals). RESULTS: Blood pressure in the animals treated with N(G)-nitro-L-arginine methyl ester significantly increased compared with that in the control group and heart rate significantly decreased immediately after nitric oxide synthase blockade. Blood pressure then trended downward as gestation progressed, until the difference between the control group and the group treated with N(G)-nitro-L-arginine methyl ester became nonsignificant after day 17. Refractoriness to nitric oxide synthase blockade was especially evident in the diastolic pressure. Systolic, diastolic, and mean blood pressures in the rats treated with N(G)-nitro-L-arginine methyl ester were again significantly higher than those in the control group immediately after delivery and remained so despite a lower heart rate until the experiment was ended on postpartum day 6. CONCLUSIONS: Radiotelemetry can be used to monitor heart rate and intra-arterial blood pressure in unstressed, unrestrained animals. Chronic inhibition of nitric oxide does not cause sustained hypertension throughout pregnancy. Nitric oxide does not appear to be the only factor responsible for the vascular changes in pregnancy. The factors responsible for the refractoriness to nitric oxide synthase blockade are specific to pregnancy and disappear immediately after delivery.",
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AU - Saade, George

AU - Buhimschi, Irina A.

AU - Garfield, Robert E.

PY - 1999

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N2 - OBJECTIVES: The objective of this study was to determine the effect of chronic nitric oxide synthase inhibition on heart rate and intravascular blood pressure in unrestrained pregnant rats as recorded by radiotelemetry. STUDY DESIGN: Heart rate and systolic and diastolic blood pressures were monitored beginning with day 6 of pregnancy and until 1 week post partum with a radiotelemetric device. On day 10 of pregnancy osmotic minipumps were implanted subcutaneously and loaded to continuously deliver N(G)-nitro-L- arginine methyl ester (50 mg/d per rat, n = 6 animals) or vehicle (control group, n = 6 animals). RESULTS: Blood pressure in the animals treated with N(G)-nitro-L-arginine methyl ester significantly increased compared with that in the control group and heart rate significantly decreased immediately after nitric oxide synthase blockade. Blood pressure then trended downward as gestation progressed, until the difference between the control group and the group treated with N(G)-nitro-L-arginine methyl ester became nonsignificant after day 17. Refractoriness to nitric oxide synthase blockade was especially evident in the diastolic pressure. Systolic, diastolic, and mean blood pressures in the rats treated with N(G)-nitro-L-arginine methyl ester were again significantly higher than those in the control group immediately after delivery and remained so despite a lower heart rate until the experiment was ended on postpartum day 6. CONCLUSIONS: Radiotelemetry can be used to monitor heart rate and intra-arterial blood pressure in unstressed, unrestrained animals. Chronic inhibition of nitric oxide does not cause sustained hypertension throughout pregnancy. Nitric oxide does not appear to be the only factor responsible for the vascular changes in pregnancy. The factors responsible for the refractoriness to nitric oxide synthase blockade are specific to pregnancy and disappear immediately after delivery.

AB - OBJECTIVES: The objective of this study was to determine the effect of chronic nitric oxide synthase inhibition on heart rate and intravascular blood pressure in unrestrained pregnant rats as recorded by radiotelemetry. STUDY DESIGN: Heart rate and systolic and diastolic blood pressures were monitored beginning with day 6 of pregnancy and until 1 week post partum with a radiotelemetric device. On day 10 of pregnancy osmotic minipumps were implanted subcutaneously and loaded to continuously deliver N(G)-nitro-L- arginine methyl ester (50 mg/d per rat, n = 6 animals) or vehicle (control group, n = 6 animals). RESULTS: Blood pressure in the animals treated with N(G)-nitro-L-arginine methyl ester significantly increased compared with that in the control group and heart rate significantly decreased immediately after nitric oxide synthase blockade. Blood pressure then trended downward as gestation progressed, until the difference between the control group and the group treated with N(G)-nitro-L-arginine methyl ester became nonsignificant after day 17. Refractoriness to nitric oxide synthase blockade was especially evident in the diastolic pressure. Systolic, diastolic, and mean blood pressures in the rats treated with N(G)-nitro-L-arginine methyl ester were again significantly higher than those in the control group immediately after delivery and remained so despite a lower heart rate until the experiment was ended on postpartum day 6. CONCLUSIONS: Radiotelemetry can be used to monitor heart rate and intra-arterial blood pressure in unstressed, unrestrained animals. Chronic inhibition of nitric oxide does not cause sustained hypertension throughout pregnancy. Nitric oxide does not appear to be the only factor responsible for the vascular changes in pregnancy. The factors responsible for the refractoriness to nitric oxide synthase blockade are specific to pregnancy and disappear immediately after delivery.

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KW - Hypertension

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KW - Preeclampsia

KW - Pregnancy

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