Pharmacological blockade of blood pressure and heart rate increases following milk ingestion in 15-day-old SHR and WKY rat pups

The effects of hexamethonium, a ganglionic blocker, on blood pressure (BP) and heart rate (HR) responses to milk ingestion were assessed in awake, 15-day-old spontaneously hypertensive rats (SHR) and their normotensive progenitor strain, Wistar-Kyoto rats (WKY) using two methods of milk delivery. SHRs had larger increases in BP compared to WKYs, but WKYs exhibited larger increases in HR following milk ingestion from an anesthetized dam. BP responses to milk ingestion from a tongue cannula were also larger in SHRs. Administration of hexamethonium prior to milk delivery resulted in a drop in BP following milk ingestion in both milk delivery situations for each strain. The results suggest that SHRs exhibit exaggerated sympathetic activation to milk ingestion compared to WKYs, and that in both strains, cardiovascular responses to feeding are modulated by the presence of the dam.