Retching for greatness
IF YOU ABSOLUTELY HAD TO THROW UP, THE LAST YEAR OR two was definitely the time to do it. Never in my recollection has the country gone through such a barf-friendly period. It was a time when the movie Wayne’s World introduced us to more synonyms for throwing up than the Eskimos have for snow; a time when weightless shuttle astronauts studying space sickness gave a whole new meaning to the up in upchuck; a time when President Read-My-Lips-But-From-a-Distance Bush launched Operation Dessert Storm, a devastating new weapon in America’s on-going trade war with Japan. (Okay, okay, I know it’s not fair to make fun of the president; we’ve all had at least one episode of surprise spew in our lives. It’s just that most of us do it over a prime rib, not a prime minister. Maybe what the president meant to promise in 1988 was a thousand pints of something.)
More important than all these developments, however, was last year’s meeting of the little-known but well-respected Club Emesis. Emesis, in case you don’t know, is the term doctors use among themselves when they’re talking about throwing up. Even the doctors themselves can’t tell you why they don’t just say “throwing up,” but many people believe the practice has its roots in the same sort of primitive instinct that makes IRS officials say “taxpayer invoice” when they mean “bill,” NASA spokesmen say “milestone interface chart” when they mean “schedule,” and potential dates say “I have to wash my hair” when they mean “I’ll go out with you again when pigs fly.”
Club Emesis got its start four years ago, when a group of doctors associated with the Society for Neuroscience decided they’d like to meet and share ideas with researchers around the world who shared a special fascination with a most special physical phenomenon. Why they didn’t consider a bowling league or a pottery class I can’t imagine. But neurophysiologist Alan Miller of Rockefeller University in New York, an acknowledged leader in the barf game, helped organize the first Club Emesis meeting in Toronto in 1988, and he has kept it together through annual powwows ever since. By last year’s meeting of the Neuroscience Society the emesis confab was proudly extending a greeting to “neurobiologists who appreciate and study this behavioral response from quite different perspectives.” Of the 14,000 or so attendees at the meeting, only 25 visited the emesis group, suggesting that the different perspective most researchers would prefer is from a neighboring state.
Eager to learn more about the science of spew, I made an appointment to meet Miller at a coffee shop near his office. As this was my first encounter with one of the elders of emesis, I gave careful thought to what I should wear for the occasion, eventually settling on a handsome jacket, tie, and splash-guard ensemble. I admit that, given the indelicate nature of the topic we’d be discussing, I thought it might be wise for the hostess to seat us at an out-of-the-way table–in Chile, perhaps. In fact we were shown to a spot right next to the kitchen, which was fine with me, unless it turned out that Miller didn’t like the food; if he decided to send it back, I didn’t want to see how he planned to do it.
Miller took no notice of my queasy concerns. “Emesis is an extremely interesting, if little-understood, phenomenon,” he let me know right away. “Human beings aren’t the only creatures capable of it. Frogs do it, fish do it, so do birds, cats, and dogs. However, mice, rats, and rabbits are all incapable of throwing up. In a way, we’re lucky we have this ability. It’s one of our most adaptive traits.”
To the lay listener, Miller’s claim seems a little overblown. On my own list of great human accomplishments, I would put throwing up far from the top, well behind our mastery of fire and only a little bit ahead of our ability to make hysterically funny flatulent noises by inflating our cheeks and pressing our palms against them. Miller, however, insisted that this downplays upchuck unfairly.
“For the most part, vomiting has one purpose: to get poisonous substances out of our bodies,” he said. “In accomplishing this task, the emetic response is extraordinarily well designed.”
An episode of emesis is often triggered by afferent nerves in the digestive tract, the peripheral nerves that monitor the contents of the stomach and communicate information to the brain. Afferent nerves typically send the brain such late-breaking digestive bulletins as: “The stomach is empty–eat,” “The stomach is full–stop eating,” and “The stomach is really full–exactly how many Lorna Doones does one person need?”
Afferent nerves aren’t stimulated only by the quantity of food in the stomach, however; they’re stimulated by the content also. The Joseph McCarthys of the peripheral nervous system, these nerves are constantly on the lookout for dangerous chemicals that ordinarily don’t appear in foods but do show up if what we’ve eaten has become rancid or spoiled. If the nerves find anything like this, they promptly alert the brain, which sends back the signal to launch lunch.
BEFORE AN ACTUAL EMESIS ERUPtion can begin, the body offers us a warning, courtesy of the vague sense of unease we recognize as nausea: There is a sudden sweatiness, a tightness in the throat. At the same time, the brain snaps into action, frantically apologizing for anything we’ve done wrong in life, promising that if we can just get through this one evening alive we’ll never, never, never mix margaritas and Mallo Cups again, and calculating with Pythagorean preciseness the shortest distance between whatever patch of floor we happen to be lying on at the moment and every bathroom in the house. While all of us have experienced these ghastly feelings, not even the emesis mavens are certain just what purpose they serve.
“Some people believe that nausea is nature’s way of reminding you that what you did to get sick in the first place wasn’t good for you and discouraging you from doing it again,” Miller said. “Morning sickness that expectant mothers experience might serve a similar function, making it less likely that they’ll try new or exotic foods while they’re pregnant.” Miller’s answer makes sense, but to me it still sounds like nature’s going overboard. Even if I didn’t feel nauseous first, the sudden reappearance in an airborne column of last night’s meat loaf would be enough to talk me into pretty much anything. But maybe I’m just easily persuaded.
Although puking to purge poisons has been with us for a long time, humanity’s other major spew stimulus did not appear until relatively recently–until the invention of the boat, the airplane, and the incredibly long road trip to the Grand Canyon. That source of stomach distress is, of course: spending a week away with your entire family. Oh, and motion sickness is part of it, too.
Recently I found myself in the northernmost part of Utah, having to take a plane to the southernmost part. The only flight I could catch was aboard one of those rickety commuter planes flown by one of those glowering pilots who only took this job because all the positions for disgruntled ex-postal employees were filled. Before we even reached cruising altitude, I had begun to turn a color roughly resembling that of Fred Gwynne in full makeup. By the time the flight attendant came around to offer me today’s lunch, I was fully prepared to offer her yesterday’s in return. What, I asked Miller over our earthbound meal, could possibly account for this unbearable phenomenon, and more important, what was I doing in northernmost Utah?
Miller couldn’t help me out with the second question, but with the first one he did much better. “Motion sickness begins,” he said, “in the balance system inside the head. When the body starts moving in unfamiliar ways, that system gets confused, leading to disorientation, dizziness, and light-headedness. As it turns out, these are precisely the sensations that can be caused by any number of toxins. It’s possible that when we feel this kind of vestibular confusion, our central nervous system thinks we’ve eaten something dangerous and responds by trying to vomit out the ‘poison.'”
This theory is what led physiologists Bob Cheung and Ken Money of the Defense and Civil Institute of Environmental Medicine in Toronto to conduct a landmark cookie-tossing experiment, in which they placed dogs on playground-type swings, swung them at a constant frequency, and then timed how long it took them to blow chunks. They then removed the dogs’ vestibular systems and repeated the swing experiment. As expected, the dogs’ vomiting response was all but eliminated. These findings helped confirm two things: a) the vestibular system is indeed linked to the emesis response, and b) it’s probably not a good idea to let Cheung and Money sit with your kids.
Other hurl triggers are much less well understood, with the most mysterious of them all being the common gag reflex. Nobody knows who the first proto-human was who accidentally stuck his proto-fingers down his throat and got himself a proto-surprise, but ever since that time people have been intrigued by this unusual technique for getting the emesis train moving. The ancient Romans may have been especially adept at this skill: at banquets they would sometimes induce vomiting after one course to make room for the next. Though this indeed allowed them to increase their food consumption, it ultimately led to a marked decrease in dinner invitations, and pretty soon even the Visigoths wouldn’t have them over.
“It’s not at all clear why sticking your fingers down your throat should make you vomit,” says Miller. “The only thing that makes sense is that there are afferents in the upper airway that perceive the fingers as an obstruction and try to clear them away. But it would seem that the body could do this more easily by coughing or sneezing than through vomiting or the gag reflex.” (Miller, by the way, is careful about his use of the term gag reflex, since there are technically two types. The second one, however, usually involves joy buzzers and mail-order plastic vomit and is therefore not studied by emesis purists.)
Another, even more mysterious spew situation is the phenomenon of collective vomiting. As anyone who grew up in a multichild family or lived in a fraternity where kegs of beer the size of ’62 Ramblers were consumed knows, when one person in a group gets the barf ball rolling, others present usually start to feel the urge, too. While such empathetic emesis can be absolute murder on carpets and upholstery, Miller and others believe it may well be a highly adaptive trait. Back in our early hunter-gatherer days, everybody in a tribe ate the same thing. If one person got sick after a meal, it therefore made good survival sense for everyone else to purge dinner, too.
WITH THE HELP OF THEORETICAL research like Miller’s and Cheung’s, scientists elsewhere are taking that next slippery step up the emesis slope and studying not just how the upchuck machinery works but how it can be shut down. At the Armed Forces Radio Biology Research Institute in Bethesda, Maryland, for example, military doctors are investigating the effect radioactivity has on the body and why it so often leads to an emesis eruption. The institute began its studies in 1960–when the pranksters in the Pentagon and the Kremlin were at their thermonuclear zaniest–and has kept at it ever since. True, most military observers agree that radiation research is a little pointless after the end of the cold war, but when you’re dealing with a branch of government that’s been known to spend $72,000 for a spatula, anything’s possible.
“Our work is in a state of flux right now,” says institute physiologist Gregory King, “but the initial objective of the research was to determine how ionizing radiation triggers emesis and whether we might be able to counteract it in some way.”
Working with animal patriots that volunteered to be irradiated, King and others have found that when the abdominal area is exposed to radioactivity, the resulting inflammation leads to the release of a number of neurotransmitters, specifically serotonin. When excess serotonin is released, it stimulates the afferent nerves the same way some poisons do, erroneously signaling the brain that there’s something fishy down here and that it might be time to cast it out.
“The discovery of this mechanism,” says King, “suggested that one way to combat radiation-related emesis is to give people serotonin antagonists that block the receptor sites and prevent the neurotransmitter from binding. It’s possible that something like this could be used as a sort of pretreatment before soldiers go into a nuclear battlefield.”
Of course, most well-trained American soliders preparing to walk into a nuclear battlefield are less worried about regurgitating than evaporating. However, serotonin antagonists are already being used successfully with cancer patients undergoing radiation treatment and chemotherapy–both of which trigger serotonin release.
In other labs around the world, retch research is proceeding apace; much of it will be presented at the next meeting of the emesis group, which promises to be rich with gossip from every corner of the puke world. At NASA doctors are still collating data from 1991’s all-medical shuttle flight, and they are now working with in-flight injections of the brain-stem blocker promethazine hydrochloride, believing it may at last eliminate the problem of space sickness; in Ireland researchers are studying ways to treat nausea with acupuncture; and in the Netherlands investigators are looking into the apparent ability of gingerroot to reduce nausea and vomiting–proving once again that your mother was right when she gave you ginger ale for a stomachache. (The same researchers, by the way, had already shown that if you don’t put that stick down this instant you will indeed put somebody’s eye out and that if you make that face one more time you do have a 73 percent chance of its freezing that way.)
No matter how far emesis research advances, of course, there will always be some upchuck mysteries that will never be answered. Will mothers of newborns ever realize that what may start out as “spit up” becomes just plain barf again the moment it hits your new sport coat? Does Hollywood realize that the title of the Mickey Rourke movie Barfly is actually the adverbial form of the word barf? Does Rourke himself ever make you feel kind of barfly? Does Romano cheese smell that way on purpose?
While all these questions are good ones, I confess that I will not be doing my part to answer them. Always a squeamish sort, I’d just as soon maintain a discreet distance from the hurl world, keeping my own receptor sites blocked, my own afferent nerves quiet, and my own upchuck down. If that means missing out on one of our species’ most adaptive traits, I’ll gladly take a step or two down the evolutionary ladder. Heights make me nauseous anyway.
COPYRIGHT 1993 Discover
COPYRIGHT 2004 Gale Group