What question did this study set out to answer?

To determine the functional roles of specific nitric oxide synthase (NOS) isoforms in the rostral ventrolateral medulla in regulating cardiac-sympathetic reflexes.

August 14, 2009AJP Heart and Circulatory PhysiologyOpen Access

Nitric oxide in rostral ventrolateral medulla regulates cardiac-sympathetic reflexes: role of synthase isoforms

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Population

Adult cats of either sex (3-4 kg), anesthetized with ketamine and alpha-chloralose.

Comparison

Unilateral rostral ventrolateral medulla… vs Unilateral rVLM microinjection of inactive…

Design

Preclinical, Animals were randomly divided into the following seven groups

Authors

ZGZhi‐Ling GuoGeneral Cardiology STStephanie C. Tjen‐A‐LooiPreventive Cardiology LFLiang‐Wu FuUniversity of California, Irvine

Discussion

Member takes

Implication

Supports nNOS role in feline rVLM reflexes; hypothesis-generating with no immediate clinical implications.

Key Points

To determine the functional roles of specific nitric oxide synthase (NOS) isoforms in the rostral ventrolateral medulla in regulating cardiac-sympathetic reflexes.
Assessed changes in mean arterial blood pressure and renal sympathetic nerve activity in anesthetized cats following epicardial bradykinin application and unilateral microinjections of selective and nonselective NOS inhibitors into the rostral ventrolateral medulla.
Performed electrophysiological recordings and 7-nitroindazole iontophoresis on identified sympathoexcitatory medullary neurons during epicardial bradykinin stimulation.
Microinjection of the nonselective NOS inhibitor L-NAME or the specific nNOS inhibitor 7-nitroindazole significantly attenuated bradykinin-induced increases in mean arterial pressure and renal sympathetic nerve activity (both P < 0.05), while iNOS and eNOS inhibitors produced no significant effect.
Iontophoresis of the nNOS inhibitor 7-nitroindazole significantly reduced the elevated discharge rates of cardiovascular sympathoexcitatory medullary neurons during cardiac bradykinin stimulation (P < 0.05).

Structured PICO

Population

Adult cats of either sex (3-4 kg), anesthetized with ketamine and alpha-chloralose.

Intervention

Unilateral rostral ventrolateral medulla (rVLM) microinjection of nonselective NOS inhibitor (N(omega)-nitro-L-arginine methyl ester [L-NAME], 50 nmol/50 nl), specific nNOS inhibitor (7-nitroindazole [7-NI], 5-10 pmol/50 nl), iNOS inhibitor (N(6)-(1-iminoethyl)-L-lysine [L-NIL], 250 pmol/50 nl), eNOS inhibitor (N(5)-(1-iminoethyl)-L-ornithine [L-NIO], 250 nmol/50 nl), or iontophoresis of 7-NI (0.1 mM).

Comparator

Unilateral rVLM microinjection of inactive isomer (N(omega)-nitro-D-arginine methyl ester [D-NAME], 50 nmol/50 nl) or vehicle (3-6% methanol or artificial cerebrospinal fluid).

Outcome

Changes in mean arterial blood pressure and renal sympathetic nerve activity elicited by epicardial application of bradykinin (1-10 microg/ml, 50 microl).surrogate

In a feline model, neuronal nitric oxide synthase (nNOS) in the rostral ventrolateral medulla mediates sympathoexcitatory cardiovascular reflexes induced by cardiac stimulation.

Cite This Study

Guo et al. (2009) studied this question.

synapsesocial.com/papers/6a707e2aa7fbea1e44081950 https://doi.org/10.1152/ajpheart.00209.2009

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Nitric oxide in rostral ventrolateral medulla regulates cardiac-sympathetic reflexes: role of synthase isoforms

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

Nitric oxide in rostral ventrolateral medulla regulates cardiac-sympathetic reflexes: role of synthase isoforms

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

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